10 biggest upsets in Champions League history: The magical night in Istanbul, Real Madrid’s 2 humiliating defeats

In the theater of European football, the Champions League is not merely a tournament; it is a high-stakes arena where financial superpowers and tactical masterminds collide. Every season, the "Old Guard" of Europe, clubs with billion-dollar valuations and trophy cabinets overflowing with silver, enter the fray expecting total domination. Yet, history has proven that even the most sophisticated war machines can be dismantled by the sheer willpower of a disciplined underdog. 

The following report by Livescorecz.net analyzes the biggest upsets in Champions League history, where determination often overcomes destiny.

10 biggest upsets in Champions League history

10. RC Lens 2-1 Arsenal (2023/24)

Arsenal, a "well-drilled, title-chasing machine" under Mikel Arteta, returned to the competition as heavy favorites. In contrast, Lens was making only their third appearance after a 20-year hiatus. Despite Arsenal taking an early lead through Gabriel Jesus, Lens, whose squad cost roughly half a billion less than their opponents, fought back with a sensational goal from Adrien Thomasson. The turning point came in the second half when Elye Wahi netted the winner, securing a -1 victory. 

This result left Arsenal stunned, though they eventually reached the quarter-finals, while Lens finished third in the group. Arteta later remarked, "In the Champions League, if you don't take your chances and you give something to the opponent, it's difficult to win."

9. Manchester United 2-3 Galatasaray (2023/24)

United entered the game in a "state of crisis," yet they were still expected to beat a Turkish side that hadn't won a Champions League away game in 5 years. Rasmus Hojlund gave United the lead twice, but a calamitous defense and a Casemiro red card allowed Wilfred Zaha and Mauro Icardi to seal a historic win for Galatasaray. This loss contributed to United’s humiliating exit at the bottom of their group.

8. Real Madrid 1-2 FC Sheriff (2021/22)

Real Madrid, the 15-time kings of Europe, were shocked at the Bernabeu by a team making its tournament debut. Sebastien Thill’s 90th-minute thumping strike secured the biggest win in Sheriff’s history. Despite this "monumental upset," Madrid showed the resilience of a true empire, going on to win the trophy that year by beating Liverpool in the final. Sheriff captain Frank Castaneda stated, "For us, this is a dream come true to win here."

7. FC Basel 2-1 Manchester United (2011/12)

Coming off a final appearance the previous year, United only needed a draw to progress. However, Swiss side Basel, inspired by Xherdan Shaqiri, outplayed the Premier League champions. This defeat relegated United to the Europa League, a massive financial and sporting blow. 

6. Manchester United 1-1 Porto (2003/04)

United faced a Porto side led by a young, ambitious Jose Mourinho. After losing the first leg 2-1, United led 1-0 and seemed set to advance on away goals until Costinha scored an injury-time equalizer. Mourinho’s iconic run down the touchline signaled the arrival of a new tactical genius. Porto went on to win the Champions League that year, their second title (the first being in 1987), while United’s early exit left the club in shock.

5. Barcelona 1-2 Rubin Kazan (2009/10)

This was Pep Guardiola’s legendary "Treble" winning side, yet they were silenced at the Camp Nou by Champions League debutants from Russia. Rubin Kazan had only three shots compared to Barcelona’s 22, but clinical finishing by Aleksandr Ryazantsev and Karadeniz secured the win. Guardiola later noted, "To understand how difficult this competition is, you only have to look at this result." Barcelona still won the group and reached the semi-finals, but their invincibility had been breached.

4. Celtic 2-1 Barcelona (2012/13)

In a match where Barcelona held 73-84% possession and completed nearly 1,000 passes, Celtic’s "Great Wall" of defense held firm. Goals from Victor Wanyama and Tony Watt secured a victory that remains a legendary night in Glasgow. Rodri later famously complained about such defensive styles in modern football, but Neil Lennon hailed his players, saying, "This is one of the greatest nights in the club's recent history."

3. AS Monaco 3-1 Real Madrid (2003/04)

Real’s "Galacticos" led 4-2 from the first leg, but they were haunted by their own player, Fernando Morientes, who was on loan at Monaco. Morientes scored a crucial goal to help Monaco advance on away goals. This upset ended the era of Galactico dominance in Europe for several years, while Monaco reached the final for the first time.

2. Deportivo La Coruna 4-0 AC Milan (2003/04)

Milan, the reigning champions with stars like Kaka and Pirlo, held a 4-1 lead from the first leg. In a display of pure defiance, Deportivo scored three goals in the first half alone. Fran’s late fourth goal completed a 5-4 aggregate comeback. Deportivo became the first team in the modern era to overturn a three-goal first-leg deficit.

1. Liverpool 3-3 AC Milan (2004/05)

While both are giants, the "upset" lies in the match progression. Trailing 3-0 at halftime against a star-studded Milan, Liverpool were dead and buried. In six minutes of madness, Steven Gerrard and his teammates leveled the score, eventually winning on penalties. 

Liverpool claimed their 5th title, while Milan’s players were left in a state of trauma. Andrea Pirlo later wrote in his autobiography that he considered retiring after that night in Istanbul.

List of the top 10 biggest upsets in Champions League history:

Liverpool 3-3 AC Milan (2004/05 Final)

Deportivo La Coruna 4-0 AC Milan (2003/04 Quarter-final)

AS Monaco 3-1 Real Madrid (2003/04 Quarter-final)

Celtic 2-1 Barcelona (2012/13 Group Stage)

Barcelona 1-2 Rubin Kazan (2009/10 Group Stage)

Manchester United 1-1 Porto (2003/04 Round of 16)

FC Basel 2-1 Manchester United (2011/12 Group Stage)

Real Madrid 1-2 FC Sheriff (2021/22 Group Stage)

Manchester United 2-3 Galatasaray (2023/24 Group Stage)

RC Lens 2-1 Arsenal (2023/24 Group Stage)

The history of the European Cup reminds us that reputation alone cannot win matches. Even the most successful clubs, such as Real Madrid, Barcelona, and Man United have frequently become unwilling victims in the list of the biggest upsets in Champions League history curated by Livescorecz.net. Which of these historic nights do you remember most vividly?

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