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Biggest Upsets in European Football: Top 10 of All Time

Sheriff Tiraspol, in their first Champions League season, beat 13-time European champions Real Madrid at the Bernabéu despite a 1.4% pre-match chance.

  • No. 1: Sheriff Tiraspol 2-1 Real Madrid (2021)
  • 10 places

01Final list

The leading AIs built their own top-ten lists independently. Above is one combined result that is easy to check: every place has a reason, the AIs that included it and, where the AIs gave one, a source.

Order: from most to least AI agreement.

A bright badge means this AI put the entry on its list. A dim badge means it did not.

  1. 1

    Sheriff Tiraspol 2-1 Real Madrid (2021)

    A Moldovan-league debutant won at the Bernabéu against 13-time champions with a 1.4% pre-match chance (Gracenote). Bookmakers had them at +2700, about 3.6% before margin.

    Included it: Claude, Meta, Gemini, Kimi, DeepSeek, StepFun.

    In their lists: Claude: 1 · Meta: 1 · Gemini: 1 · Kimi: 1 · DeepSeek: 1 · StepFun: 1

    What each AI noted 6
    • Claudeplace 1

      A debutant with a reported $14m squad beat a $872m side with a 1.4% pre-match chance, the lowest on Gracenote's list since 2010.

      Source ↗
    • Metaplace 1

      Elo gap 478 points: Real 2262 vs Sheriff 1784 – biggest Elo shock in Champions League history per academic paper

      Source ↗
    • Geminiplace 1

      Moldovan debutants with an implied 1.4% win probability defeated 13-time European champions Real Madrid at the Santiago Bernabéu.

    • Kimiplace 1

      Sheriff were +2700 at Caesars—3.6% raw implied probability—and still won at the Bernabéu.

      Source ↗
    • DeepSeekplace 1

      Gracenote gave Sheriff a 1.4% chance of winning at the Bernabéu — the lowest pre-match win probability recorded since the Euro Club Index began in 2010.

      Source ↗
    • StepFunplace 1

      A debutant from a breakaway state beat 13-time champions at the Bernabéu at +2700 — the biggest underdog price in three Champions League seasons.

      Source ↗
    6 AIs put it here
    Source ↗
  2. 2

    Basel 2-1 Manchester United (2011)

    The highest stakes of the group-stage shocks: three-time champions United needed only a draw and started Rooney and De Gea, but Basel's 2-1 knocked them out. A 1% pre-match figure comes from one source.

    Included it: Claude, Gemini, Kimi, DeepSeek, StepFun. Did not include: Meta.

    In their lists: Claude: 10 · Gemini: 8 · Kimi: 9 · DeepSeek: 4 · StepFun: 9

    What each AI noted 5
    • Claudeplace 10

      A draw would have sent United through; Basel's win in December 2011 knocked a three-time European champion out in the group stage.

      Source ↗
    • Geminiplace 8

      Swiss underdogs Basel eliminated Sir Alex Ferguson's 2011 finalists from the Champions League group stage in a straight knockout decider.

    • Kimiplace 9

      Basel made one point enough to knock out a Manchester United side that had reached the previous final.

      Source ↗
    • DeepSeekplace 4

      Basel were given about a 1-in-100 chance of beating United; the win eliminated the three-time European champions.

      Source ↗
    • StepFunplace 9

      A modest Swiss club dumped a full-strength United — Rooney, Ferdinand, De Gea — out of the Champions League.

      Source ↗
    5 AIs put it here
    Source ↗
  3. 3

    Rubin Kazan 2-1 Barcelona (2009)

    A Champions League debutant beat the reigning champions' full-strength XI (Messi, Xavi, Iniesta, Ibrahimović) at Camp Nou with three shots to Barcelona's 22. One report says 24.

    Included it: Claude, Gemini, Kimi, StepFun. Did not include: Meta, DeepSeek.

    In their lists: Claude: 2 · Gemini: 3 · Kimi: 3 · StepFun: 5

    What each AI noted 4
    • Claudeplace 2

      The holders lost at the Camp Nou despite 24 shots to 3, to a debutant that scored after 70 seconds.

      Source ↗
    • Geminiplace 3

      Russian debutants stunned Pep Guardiola's sextuple-winning Barcelona at Camp Nou with an Elo mismatch exceeding 400 points.

    • Kimiplace 3

      Rubin made three shots against Barcelona's 22—and still left Camp Nou with the champion's scalp.

    • StepFunplace 5

      A modest Russian club travelled to the Camp Nou and beat the reigning European champions — Barcelona's first loss of the season.

    4 AIs put it here
    Source ↗
  4. 4

    Celtic 2-1 Barcelona (2012)

    Gracenote gave Celtic 7.1%, its second-biggest shock since 2010. But Celtic are 1967 European champions and Champions League regulars, so they rank below the debutants. Their possession is quoted at 11–27%.

    Included it: Claude, Gemini, Kimi, DeepSeek. Did not include: Meta, StepFun.

    In their lists: Claude: 5 · Gemini: 7 · Kimi: 8 · DeepSeek: 2

    What each AI noted 4
    • Claudeplace 5

      Gracenote gave Celtic 7.1%, second on its shock list, but this is the weakest underdog on the list: Celtic are a regular in the competition.

      Source ↗
    • Geminiplace 7

      Celtic recorded just 16.4% possession and 5 shots to beat Messi's peak Barcelona on the 125th anniversary of the Scottish club.

    • Kimiplace 8

      Tony Watt, signed for £50,000, scored the goal that downed Lionel Messi's Barcelona.

      Source ↗
    • DeepSeekplace 2

      Celtic won with 7.1% pre-match probability and just 11% possession, ending Barcelona's 12-game unbeaten run.

      Source ↗
    4 AIs put it here
    Source ↗
  5. 5

    BATE Borisov 3-1 Bayern Munich (2012)

    BATE beat Bayern by two goals in Minsk in the season Bayern won the treble; Neuer, Lahm, Schweinsteiger and Ribéry played. There is no reliable pre-match probability (a fan poll said 3%).

    Included it: Claude, Meta, Kimi. Did not include: Gemini, DeepSeek, StepFun.

    In their lists: Claude: 6 · Meta: 3 · Kimi: 2

    What each AI noted 3
    • Claudeplace 6

      Bayern were chasing a first treble that season and conceded three to a Belarusian side, who also won away at Lille.

      Source ↗
    • Metaplace 3

      Belarus champions hit treble winners 3-1 – shock of group stage with 16,000 crowd

      Source ↗
    • Kimiplace 2

      BATE turned a pre-match fan vote of 3% into a two-goal defeat of a four-time champion.

    3 AIs put it here
    Source ↗
  6. 6

    Bodø/Glimt 2-1 Inter Milan (2026)

    Bodø/Glimt were 35th in UEFA's club ranking against third-placed Inter, last season's finalists, and won at San Siro to go through 5-2. They already led 3-1 from the first leg. One source dates the tie to 2025.

    Included it: Kimi, StepFun. Did not include: Claude, Meta, Gemini, DeepSeek.

    In their lists: Kimi: 4 · StepFun: 3

    What each AI noted 2
    • Kimiplace 4

      Bodø/Glimt took a 35th-to-3rd coefficient gap to San Siro and won the tie's live second leg.

    • StepFunplace 3

      A 43,000-person Arctic town on a €30-40m budget eliminated a Champions League finalist — after a 99.7% elimination probability earlier in the campaign.

      Source ↗
    2 AIs put it here
    Source ↗
  7. 7

    Deportivo La Coruña 4-0 AC Milan (2004)

    Defending champions Milan, with six European Cups, led 4-1 from the first leg and lost 4-0 at Riazor. Deportivo were not a minnow, so this ranks below the true small-club shocks.

    Included it: Gemini, StepFun. Did not include: Claude, Meta, Kimi, DeepSeek.

    In their lists: Gemini: 5 · StepFun: 2

    What each AI noted 2
    • Geminiplace 5

      Deportivo erased a 4–1 first-leg deficit by dismantling Carlo Ancelotti's reigning European champions 4–0 at Riazor.

    • StepFunplace 2

      Overturned a 4-1 first-leg deficit with a four-goal demolition of the defending champions — the biggest single-match comeback margin over a giant.

    2 AIs put it here
    no source given
  8. 8

    Aberdeen 2-1 Real Madrid (1983 Cup Winners' Cup final)

    In a trophy final against six-time European champions, Ferguson's Aberdeen won in extra time with John Hewitt's 112th-minute goal. No pre-match probability exists for 1983.

    Included it: Claude, StepFun. Did not include: Meta, Gemini, Kimi, DeepSeek.

    In their lists: Claude: 4 · StepFun: 4

    What each AI noted 2
    • Claudeplace 4

      A final, not a group game: Alex Ferguson's Aberdeen beat a Real Madrid side that had already won six European Cups, in extra time.

      Source ↗
    • StepFunplace 4

      Alex Ferguson's small Scottish club beat six-time European Cup kings Real Madrid with a 112th-minute winner in Gothenburg.

      Source ↗
    2 AIs put it here
    Source ↗
  9. 9

    Steaua Bucharest vs Barcelona (1986 European Cup final)

    Duckadam saved all four Barcelona penalties in a final played in Seville. At the time Barcelona had never won the European Cup, so they were a smaller 'giant' than their later reputation suggests.

    Included it: Gemini, StepFun. Did not include: Claude, Meta, Kimi, DeepSeek.

    In their lists: Gemini: 4 · StepFun: 7

    What each AI noted 2
    • Geminiplace 4

      Goalkeeper Helmuth Duckadam saved all four Barcelona penalties in Seville to deliver Eastern Europe's first European Cup.

    • StepFunplace 7

      Helmuth Duckadam saved all four Barcelona penalties — Steaua remain the only club ever to beat Barcelona in a European final.

      Source ↗
    2 AIs put it here
    Source ↗
  10. 10

    APOEL 1-0 Lyon, 4-3 on penalties (2012)

    A Cypriot club reached the Champions League quarter-finals by beating Lyon on penalties in a knockout tie. Lyon had no European trophy, which makes them the smallest giant on this list.

    Included it: Meta, Gemini. Did not include: Claude, Kimi, DeepSeek, StepFun.

    In their lists: Meta: 5 · Gemini: 9

    What each AI noted 2
    • Metaplace 5

      Cypriot club with €14m budget beats 7x French champs to reach quarter-finals – only Cypriot QF ever

      Source ↗
    • Geminiplace 9

      Cypriot underdogs APOEL eliminated French seven-time champions Lyon to become the first Cypriot club to reach the Champions League quarterfinals.

    2 AIs put it here
    Source ↗

More about the top three ↓

02More about the top three

The ranking is above. Here is more about the three places at the top: what they are, why they are here, and what is worth knowing.

The three are not measured the same way: Sheriff has a 1.4% chance from Gracenote, Basel a 1% figure from one source, and Rubin only an Elo gap of more than 400 points.

1Sheriff Tiraspol 2-1 Real Madrid (2021)

No. 1 — Sheriff Tiraspol 2-1 Real Madrid (2021). On the lists of 6 of 6 AIs; median place there: 1. The AIs ranked it first because the lowest pre-match chance on record, 1.4%, still ended in a win over 13-time champions.

Did you know

  • After the Real Madrid win, Sheriff also became the first Moldovan side to play in a European knockout round. They beat Braga 2-0 at home, lost 2-0 away, then lost 3-2 on penalties.

    Source ↗
What it is
Debutant Sheriff won 2-1 at Real Madrid in 2021.
Its edge
Lowest pre-match win chance of the three: 1.4%.
Who should know
Useful for anyone wondering how unlikely a football shock can really get.
  • Pre-match win chance1.4% pre-match chance
Why it is here

  • Sheriff was playing its first Champions League group season, yet won at the Bernabéu with a goal in the 89th minute. That left the club on six points from six games, top of Group D.

    Source ↗

  • Sheriff was founded only in 1997. This is the youngest club of the top three, and it beat Real Madrid in a live group game, not a dead rubber.

    Source ↗
Did you know

  • Sheriff's squad has players from 16 countries, and only about a third are Moldovan. The club also owns a five-star hotel and a college next to its stadium, which holds 12,746 people.

    Source ↗
History

  • In April 1997 the club took its name from its main sponsor, the Sheriff company, which remains a key sponsor. It was founded in 1997 as Tiras Tiraspol and renamed the following year. — (voice only)

    Source ↗
Keep in mind

  • Sheriff is based in Tiraspol, in Transnistria, a breakaway state. The club is named after the region's second-largest company, so the win was not a simple underdog story for everyone.

    Source ↗

  • Real did score first through a Benzema penalty, and the winner came late. Real coach Ancelotti said: "Everything went well for them (Sheriff) while everything we did turned out badly." Luck played a part.

    Source ↗
Where to go further

  • Read the ESPN match report for Real Madrid vs Sheriff. Start with how Sheriff scored its first goal, then look at the stats to see how one-sided the game was. Reading takes about ten minutes.

    Source ↗
Compare the top three ↓

2Basel 2-1 Manchester United (2011)

No. 2 — Basel 2-1 Manchester United (2011). On the lists of 5 of 6 AIs; median place there: 9. The AIs placed it second for the stakes: United needed only a draw, and the loss knocked them out of the group.

Did you know

  • Basel didn't stop at United. In the next round they beat Bayern Munich 1–0 at home in the first leg. Bayern won the return in Munich and went through 7–1 on aggregate, with Mario Gomez scoring four in that second leg.

    Source ↗
What it is
Basel beat Manchester United 2-1 in December 2011.
Its edge
Highest stakes of the three: United's whole group stage hung on this game.
Who should know
Useful for seeing how a shock can cost a giant its whole season.
  • Pre-match win chanceAbout 1% (one source)
Why it is here

  • United needed only a draw in Basel to advance. They lost 2-1, with Basel's second goal in the 84th minute. Basel finished on 11 points and United on 9, two behind. That makes this the highest-stakes match of the three.

    Source ↗

  • United were three-time European champions. The article says they had reached the knockout round in 15 of 16 Champions League seasons, so this was their one miss in that span.

    Source ↗
Did you know

  • Basel's win came on the same night as another English exit. Manchester City also failed to reach the last 16, so both Manchester clubs were out of the Champions League on 7 December 2011. Both then dropped down to the Europa League.

    Source ↗
History

  • In 1998 the old St. Jakob Stadium was demolished to make way for a new one. From 1998 to 2001 the club played its home games at the smaller Stadion Schützenmatte. — (voice only)

    Source ↗
Keep in mind

  • United needed only a draw. The report says a David de Gea error led to Basel's first goal, and Nemanja Vidic was injured in the 42nd minute. Ferguson said: "We were careless."

    Source ↗

  • The loss had a price: United finished third in the group. They dropped into the second-tier Europa League and played there from the following February.

    Source ↗
Where to go further

  • Read the ESPN match report for FC Basel vs Manchester United. Start with the goal times, and notice how late United's only goal came. Reading takes about ten minutes.

    Source ↗
Compare the top three ↓

3Rubin Kazan 2-1 Barcelona (2009)

No. 3 — Rubin Kazan 2-1 Barcelona (2009). On the lists of 4 of 6 AIs; median place there: 3. The AIs put it third because Rubin won at Camp Nou against the champions with very few shots, though the odds were less extreme.

Did you know

  • Rubin qualified for the 2009-10 group stage by winning the 2008 Russian league. That made them the easternmost team ever to play in the Champions League.

    Source ↗
What it is
Debutant Rubin Kazan beat holders Barcelona 2-1 in 2009.
Its edge
Biggest gap in play: Rubin had 3 shots to Barcelona's 24.
Who should know
Useful for seeing that a team can win without controlling the game.
  • Pre-match win chanceElo gap over 400 points
Why it is here

  • Barcelona outshot Rubin 24 to 3 at Camp Nou, yet Rubin won 2-1. It was Rubin's first-ever Champions League win, in its debut season, over the defending European champions.

    Source ↗

  • Rubin scored in the 2nd minute. The loss ended Barcelona's run of 10 Champions League games without defeat. Rubin had won only one league title, in 2008.

    Source ↗
Did you know

  • Two weeks after beating Barcelona 2-1 at Camp Nou, Rubin held them to a 0-0 draw at home in Kazan. So Barcelona took only one point from their two games against Rubin.

    Source ↗
History

  • In 1994 money troubles left Rubin unable to travel, and it forfeited games. In 1996 Kazan's mayor, Kamil Iskhakov, bought the team, and the club's finances were put in order. — (voice only)

    Source ↗
Compare the top three ↓

The top three side by side

Sheriff Tiraspol 2-1 Real Madrid (2021)Basel 2-1 Manchester United (2011)Rubin Kazan 2-1 Barcelona (2009)
In the AIs' lists6 / 65 / 64 / 6
Pre-match win chance1.4% pre-match chanceAbout 1% (one source)Elo gap over 400 points
Put first byClaude, Meta, Gemini, Kimi, DeepSeek, StepFun——

Places with the same number of AIs are ordered by their average place in the AIs' own lists.

More ratings

03Worth knowing

What the AIs noticed while building the list.

Gracenote rates Sheriff's 1.4% the biggest Champions League shock since 2010; Celtic's 7.1% against Barcelona is second.

Noticed by:
Included it: Claude, DeepSeek. Did not include: Meta, Gemini, Kimi, StepFun.
Source ↗

Sources give different pre-match chances for Sheriff: 1.4% from Gracenote, but about 3.6% from the +2700 bookmaker price.

Noticed by:
Included it: Claude, Kimi, StepFun. Did not include: Meta, Gemini, DeepSeek.
Source ↗

Elo gaps depend on the database: Sheriff v Real is 478, 512 or 585 points, because eurocoeff uses today's ClubElo as a stand-in for historical ratings.

Noticed by:
Included it: Meta, Gemini, DeepSeek. Did not include: Claude, Kimi, StepFun.
Source ↗

Dead rubbers don't count as real shocks: CSKA Sofia beat Roma 3-1 despite a 347-point Elo gap, but Roma had already qualified and rotated.

Noticed by:
Included it: DeepSeek. Did not include: Claude, Meta, Gemini, Kimi, StepFun.
Source ↗

04How we counted

In plain words, no formulas.

1The question

Top 10 Biggest Upsets by Small Clubs Against European Giants

2Why this topic

Elo shows how unlikely a result was and the trophy count shows how big the beaten club was, but only a judgment on the stakes and team selection separates real shocks from dead-rubber surprises.

3Where it applies

UEFA club competitions, all eras, single matches won by the underdog

4What we looked at

  • Elo rating gap and pre-match win probability for the underdog
  • European trophies held by the beaten giant
  • Stakes of the match: a knockout tie or a live group game, not a dead rubber
  • Whether the underdog was in its first or one of its first European seasons
  • Margin of victory
  • Gracenote Euro Club Index — Pre-match win probability for every Champions League match since 2010/11 (not an Elo model)
  • ClubElo / EloFootball — Club Elo ratings and the implied chance of an underdog win; historical gaps vary by database
  • eurocoeff biggest upsets — Elo-gap table of upsets, using today's ClubElo as a stand-in for historical ratings

5Who ranked

The leading AIs, each building its own list of ten independently and naming a source for every place: Claude, Meta, Gemini, Kimi, DeepSeek, StepFun.

6How the places were set

The same entry written differently by different AIs was counted as one. The more AIs put an entry on their list, and the higher they put it, the higher its place. "AI agreement" shows how many of the AIs had it on their own list. Sources are only those the AIs found themselves; nothing was added by hand.

05Each AI's own list

🇺🇸 Claude10 places · 3 notes

The same question, answered by Claude alone. The final list above combines all the AIs.

  1. 1
    Sheriff Tiraspol 2-1 Real Madrid (Champions League, 2021)

    A debutant with a reported $14m squad beat a $872m side with a 1.4% pre-match chance, the lowest on Gracenote's list since 2010.

    Source ↗
  2. 2
    Rubin Kazan 2-1 Barcelona (Champions League, 2009)

    The holders lost at the Camp Nou despite 24 shots to 3, to a debutant that scored after 70 seconds.

    Source ↗
  3. 3
    Bodø/Glimt 3-1 Manchester City (Champions League, Jan 2026)

    A club from a town of about 55,000 won its first Champions League game by two goals, with Kasper Høgh scoring twice.

    Source ↗
  4. 4
    Aberdeen 2-1 Real Madrid (Cup Winners' Cup final, 1983)

    A final, not a group game: Alex Ferguson's Aberdeen beat a Real Madrid side that had already won six European Cups, in extra time.

    Source ↗
  5. 5
    Celtic 2-1 Barcelona (Champions League, 2012)

    Gracenote gave Celtic 7.1%, second on its shock list, but this is the weakest underdog on the list: Celtic are a regular in the competition.

    Source ↗
  6. 6
    BATE Borisov 3-1 Bayern Munich (Champions League, 2012)

    Bayern were chasing a first treble that season and conceded three to a Belarusian side, who also won away at Lille.

    Source ↗
  7. 7
    Young Boys 2-1 Manchester United (Champions League, 2021)

    19 shots to 2, a United red card and a stoppage-time winner after a Lingard backpass.

    Source ↗
  8. 8
    Slovan Bratislava 3-2 Barcelona (Cup Winners' Cup final, 1969)

    A Czechoslovak side won a European final against a giant in Basel, a high-stakes result with a one-goal margin.

    Source ↗
  9. 9
    Mechelen 1-0 Ajax (Cup Winners' Cup final, 1988)

    In their first European appearance they won the trophy without a defeat, beating a former European champion in the final.

    Source ↗
  10. 10
    Basel 2-1 Manchester United (Champions League, 2011)

    A draw would have sent United through; Basel's win in December 2011 knocked a three-time European champion out in the group stage.

    Source ↗

What Claude noticed

Gracenote's index gave Sheriff only a 1.4% chance against Real Madrid, the biggest shock since the index began in 2010. Celtic's 7.1% against Barcelona is second.

Source ↗

Sheriff's squad was reported at $14m against Real Madrid's $872m, a gap of more than 60 times.

Source ↗

The Bodø/Glimt win over City (January 2026) was the Norwegian club's first Champions League win, and Rodri was sent off.

Source ↗
🇺🇸 Meta10 places · 3 notes

The same question, answered by Meta alone. The final list above combines all the AIs.

  1. 1
    Sheriff Tiraspol 2-1 Real Madrid – Champions League group stage 28 Sep 2021

    Elo gap 478 points: Real 2262 vs Sheriff 1784 – biggest Elo shock in Champions League history per academic paper

    Source ↗
  2. 2
    Lincoln Red Imps 1-0 Celtic – Champions League 2nd qualifying round 12 Jul 2016

    Part-timers with policeman scorer vs 6x Scottish champs – 1,632 attendance Shock of Gibraltar

    Source ↗
  3. 3
    BATE Borisov 3-1 Bayern Munich – Champions League group stage 2 Oct 2012

    Belarus champions hit treble winners 3-1 – shock of group stage with 16,000 crowd

    Source ↗
  4. 4
    Artmedia Bratislava 3-2 FC Porto – Champions League group stage 28 Sep 2005

    0-2 down at Dragao to beat 2004 Champions League winners 3-2 – first Slovak point then win

  5. 5
    APOEL Nicosia 1-0 Lyon (4-3 pens) – Champions League Round of 16 7 Mar 2012

    Cypriot club with €14m budget beats 7x French champs to reach quarter-finals – only Cypriot QF ever

    Source ↗
  6. 6
    APOEL Nicosia 2-1 FC Porto – Champions League group stage 1 Nov 2011

    2-1 vs twice European Champions in Nicosia – sealed group win over Porto

    Source ↗
  7. 7
    Astana 2-2 APOEL (agg) – Champions League play-off 26 Aug 2015

    Kazakhstan's first group stage via Nemanja Maksimovic equaliser vs Cypriot champs – first Kazakh team

  8. 8
    Sheriff Tiraspol 2-0 Sporting Braga – Europa League 17 Feb 2022

    All-time high Elo 1833 after beating Braga 2-0 – Moldovan peak after Real shock

  9. 9
    Birkirkara 4-3 FC Santa Coloma (agg) – Champions League 1st qualifying 6 Jul 2010

    Maltese part-timers overturn Andorran champions 4-3 – micro-state derby where 3-goal margin is huge

    Source ↗
  10. 10
    AFC Bournemouth 2-1 Real Sociedad – Europa League debut 17 Sep 2026

    Debutants win away in San Sebastian – first ever European match win for 127-year-old club

    Source ↗

What Meta noticed

Lincoln Red Imps 1-0 Celtic is described as one of greatest shocks and Shock of Gibraltar with only 1,632 fans present

Source ↗

BATE's 3-1 vs Bayern came in season Bayern won treble – only loss before March, proving full-strength giant can lose to minnow

Source ↗

Full-strength vs rotated matters: Ancelotti fielded full-strength vs Sheriff, no excuses – ranks above dead-rubber wins

Source ↗
🇺🇸 Gemini10 places

The same question, answered by Gemini alone. The final list above combines all the AIs.

  1. 1
    Sheriff Tiraspol 2–1 Real Madrid (2021-22 UEFA Champions League)

    Moldovan debutants with an implied 1.4% win probability defeated 13-time European champions Real Madrid at the Santiago Bernabéu.

  2. 2
    Bodø/Glimt 6–1 AS Roma (2021-22 UEFA Europa Conference League)

    A club from within the Arctic Circle inflicted the first six-goal defeat of José Mourinho's 1,008-match managerial career.

  3. 3
    Rubin Kazan 2–1 Barcelona (2009-10 UEFA Champions League)

    Russian debutants stunned Pep Guardiola's sextuple-winning Barcelona at Camp Nou with an Elo mismatch exceeding 400 points.

  4. 4
    Steaua București 0–0 (2–0 p) Barcelona (1985-86 European Cup Final)

    Goalkeeper Helmuth Duckadam saved all four Barcelona penalties in Seville to deliver Eastern Europe's first European Cup.

  5. 5
    Deportivo La Coruña 4–0 AC Milan (2003-04 UEFA Champions League)

    Deportivo erased a 4–1 first-leg deficit by dismantling Carlo Ancelotti's reigning European champions 4–0 at Riazor.

  6. 6
    Artmedia Bratislava 5–0 Celtic (2005-06 UEFA Champions League Qualifiers)

    Slovakia's Artmedia shattered 1967 European champions Celtic 5–0 in Gordon Strachan's debut competitive game in charge.

  7. 7
    Celtic 2–1 Barcelona (2012-13 UEFA Champions League)

    Celtic recorded just 16.4% possession and 5 shots to beat Messi's peak Barcelona on the 125th anniversary of the Scottish club.

  8. 8
    FC Basel 2–1 Manchester United (2011-12 UEFA Champions League)

    Swiss underdogs Basel eliminated Sir Alex Ferguson's 2011 finalists from the Champions League group stage in a straight knockout decider.

  9. 9
    APOEL Nicosia 1–0 (4–3 p) Lyon (2011-12 UEFA Champions League)

    Cypriot underdogs APOEL eliminated French seven-time champions Lyon to become the first Cypriot club to reach the Champions League quarterfinals.

  10. 10
    Dinamo Zagreb 3–0 Tottenham Hotspur (2020-21 UEFA Europa League)

    With their manager imprisoned days prior, Dinamo Zagreb overturned a 2–0 deficit with a Mislav Oršić hat-trick to oust José Mourinho's Tottenham.

🇨🇳 Kimi10 places · 3 notes

The same question, answered by Kimi alone. The final list above combines all the AIs.

  1. 1
    Sheriff Tiraspol 2-1 Real Madrid (2021)

    Sheriff were +2700 at Caesars—3.6% raw implied probability—and still won at the Bernabéu.

    Source ↗
  2. 2
    BATE Borisov 3-1 Bayern Munich (2012)

    BATE turned a pre-match fan vote of 3% into a two-goal defeat of a four-time champion.

  3. 3
    Rubin Kazan 2-1 Barcelona (2009)

    Rubin made three shots against Barcelona's 22—and still left Camp Nou with the champion's scalp.

  4. 4
    Bodø/Glimt 2-1 Inter Milan (2026)

    Bodø/Glimt took a 35th-to-3rd coefficient gap to San Siro and won the tie's live second leg.

  5. 5
    Wrexham 1-0 Porto (1984)

    A fourth-tier Welsh side beat the reigning European champion 1-0, even though Porto survived the tie.

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  6. 6
    Ipswich Town 1-0 Real Madrid (1973)

    Ipswich's first European voyage ended Real Madrid's visit with a 1-0 Portman Road ambush.

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  7. 7
    Maccabi Haifa 2-0 Juventus (2022)

    Haifa kept a full-strength Juve attack scoreless and won 2-0 with a 0.75-0.48 xG edge.

  8. 8
    Celtic 2-1 Barcelona (2012)

    Tony Watt, signed for £50,000, scored the goal that downed Lionel Messi's Barcelona.

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  9. 9
    Basel 2-1 Manchester United (2011)

    Basel made one point enough to knock out a Manchester United side that had reached the previous final.

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  10. 10
    Maccabi Haifa 3-0 Manchester United (2002)

    Haifa's 3-0 is the biggest margin here, but a rotated United keeps it below the top nine.

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What Kimi noticed

Sheriff's +2700 price translated to only 3.57% raw implied probability before margin, the clearest open market measurement of a modern European giant-killing.

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Rubin Kazan's 2-1 win at Barcelona remains the ranking's most efficient smash-and-grab: three shots to Barcelona's 22.

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The Sheriff result is not discounted as a dead rubber—Group D was live—but Real did rest Modric, Asensio and Rodrygo before introducing three elite attackers after the hour.

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🇨🇳 DeepSeek10 places · 4 notes

The same question, answered by DeepSeek alone. The final list above combines all the AIs.

  1. 1
    Sheriff Tiraspol 2-1 Real Madrid (2021-22 Champions League group stage)

    Gracenote gave Sheriff a 1.4% chance of winning at the Bernabéu — the lowest pre-match win probability recorded since the Euro Club Index began in 2010.

    Source ↗
  2. 2
    Celtic 2-1 Barcelona (2012-13 Champions League group stage)

    Celtic won with 7.1% pre-match probability and just 11% possession, ending Barcelona's 12-game unbeaten run.

    Source ↗
  3. 3
    Shakhtar Donetsk 1-0 Barcelona (2023-24 Champions League group stage)

    Shakhtar's 21.9% win probability understates the shock: Barcelona had 68% possession but produced only 0.69 xG.

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  4. 4
    Basel 2-1 Manchester United (2011-12 Champions League group stage)

    Basel were given about a 1-in-100 chance of beating United; the win eliminated the three-time European champions.

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  5. 5
    Ludogorets Razgrad 2-1 Roma (2022-23 Europa League group stage)

    Roma were held to a 19.4% underdog win probability in Bulgaria, then still reached the Europa League final.

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  6. 6
    Ballkani 2-0 Dinamo Zagreb (2023-24 Conference League group stage)

    Ballkani's 305-point Elo deficit was overturned with a two-goal win in their first Conference League group campaign.

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  7. 7
    Rangers 4-2 Borussia Dortmund (2021-22 Europa League knockout play-off)

    Rangers were 15.1% underdogs at Ibrox but scored four against the 1997 European champions to take a two-goal first-leg lead.

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  8. 8
    LASK 4-3 Slavia Prague (2021-22 Conference League round of 16)

    LASK produced the single-match shock of a 309-point Elo gap, but still went out 7-5 on aggregate — a reminder that one-night upsets are not tie wins.

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  9. 9
    Olympiacos 1-0 Arsenal (2020-21 Europa League round of 16)

    Olympiacos won the second leg at the Emirates despite a 296-point Elo gap, but Arsenal still advanced 3-2 on aggregate.

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  10. 10
    CSKA Sofia 3-1 Roma (2020-21 Europa League group stage)

    CSKA's 35% win probability was unusually high for a 347-point Elo gap — Roma had already qualified, so the giant had little at stake.

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What DeepSeek noticed

Sheriff's 1.4% is the lowest pre-match win probability in the Gracenote/Euro Club Index era, lower than Celtic's famous 7.1% against Barcelona.

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Celtic beat Barcelona with only 11% possession — the most extreme statistical inversion in this top 10, and a useful check on possession-based models.

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CSKA Sofia's 35% win probability looks high for a 347-point Elo gap, but Roma had already qualified; the ranking deliberately discounts dead-rubber wins.

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LASK's 4-3 win over Slavia is the clearest case of a single-match shock that was not a tie shock: Slavia won 7-5 on aggregate.

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🇨🇳 StepFun10 places · 3 notes

The same question, answered by StepFun alone. The final list above combines all the AIs.

  1. 1
    Sheriff Tiraspol 2-1 Real Madrid (Champions League group, 28 Sep 2021)

    A debutant from a breakaway state beat 13-time champions at the Bernabéu at +2700 — the biggest underdog price in three Champions League seasons.

    Source ↗
  2. 2
    Deportivo La Coruña 4-0 AC Milan (Champions League quarter-final, 7 Apr 2004)

    Overturned a 4-1 first-leg deficit with a four-goal demolition of the defending champions — the biggest single-match comeback margin over a giant.

  3. 3
    Bodø/Glimt 2-1 Inter Milan (Champions League knockout playoff, Feb 2025; 5-2 agg)

    A 43,000-person Arctic town on a €30-40m budget eliminated a Champions League finalist — after a 99.7% elimination probability earlier in the campaign.

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  4. 4
    Aberdeen 2-1 Real Madrid (European Cup Winners' Cup final, 11 May 1983)

    Alex Ferguson's small Scottish club beat six-time European Cup kings Real Madrid with a 112th-minute winner in Gothenburg.

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  5. 5
    Rubin Kazan 2-1 Barcelona (Champions League group, 20 Oct 2009)

    A modest Russian club travelled to the Camp Nou and beat the reigning European champions — Barcelona's first loss of the season.

  6. 6
    Roma 3-0 Barcelona (Champions League quarter-final, 10 Apr 2018)

    Overturned a 4-1 first-leg beating with a three-goal win to eliminate Barcelona on away goals.

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  7. 7
    Steaua București 0-0 Barcelona, 2-0 on penalties (European Cup final, 7 May 1986)

    Helmuth Duckadam saved all four Barcelona penalties — Steaua remain the only club ever to beat Barcelona in a European final.

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  8. 8
    Copenhagen 4-3 Manchester United (Champions League group, Nov 2023)

    A last-gasp Bardghji winner sunk a full-strength Manchester United in a game the giants had to win.

  9. 9
    Basel 2-1 Manchester United (Champions League group, 7 Dec 2011)

    A modest Swiss club dumped a full-strength United — Rooney, Ferdinand, De Gea — out of the Champions League.

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  10. 10
    Red Star Belgrade 0-0 Marseille, 5-3 on penalties (European Cup final, 29 May 1991)

    A club from a war-torn Yugoslavia beat a French powerhouse in Bari to become the last Eastern European European Cup winner.

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What StepFun noticed

Bodø/Glimt come from a town of ~43,000 with a budget that was €4.2m a decade ago and €30-40m now — yet they earned €53m in a single Champions League season and knocked out Inter Milan.

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Sheriff's 2-1 win carried +2700 odds — the biggest Champions League underdog price in three seasons — at a Bernabéu hosting 13-time winners Real Madrid.

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The beaten giants rarely rotate when it matters: Basel (2011) and Copenhagen (2023) rank highly precisely because Manchester United needed the points and started near-full-strength XIs.

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