UEFA Champions League: Top 10 upsets of all-time

European football's top competition has seen its fair share of shocks over the years.

Football is arguably the most popular sport in the world, mainly due to the fact that people enjoy the adrenaline, the panache and the underdog stories surrounding the beautiful game. The stories of struggle and resilience are always cherished by fans all over the globe - specially in the UEFA Champions League. 

The underdog stories in UEFA Champions League are often appreciated because they happen rarely. It is not often that you see Celtic beating Barcelona or Bayern Munich getting humbled by BATE Borisov. 

Here are the the top 10 greatest upsets of all time in the continental tournament. 

10. FC Barcelona 1-2 Rubin Kazan (October 2009)

Camp Nou has been a fortress for FC Barcelona over the years. The Catalans may not be at their best but beating them at their own backyard takes a mammoth performance from the opposition. A similar performance was delivered by Rubin Kazan in UEFA Champions League 2009 against a Pep Guardiola led Barcelona side which had the likes of Xavi, Andres Iniesta and Lionel Messi among others. 

The Russian outfit did not hold themselves back against the Catalans and were rewarded for their positive approach in the second minute of the match. Alexander Ryazantsev found himself in a little bit of space and launched an audacious long ranger which gave Kazan the early lead. Although Barcelona equalised through Zlatan Ibrahimovic, it did not dampen the spirits of the Russians. 

Rubin Kazan were back on top again when Gökdeniz Karadeniz scored the winner. The result came as a shock to the football fraternity.

9. AS Monaco 3-1 Real Madrid (2004 Quarterfinals)

Los Blancos were a team full of stars in the early parts of the 2000s. In the summer of 2003, they signed David Beckham from Manchester United to a team which already had stars like Raul, Ronaldo Lima, Zinedine Zidane and Luis Figo. Therefore, everyone expected them to do well in the UEFA Champions League but somehow they ended the 2003-04 season trophyless.

https://www.youtube.com/watch?v=A_JN-Xb7V_0

The Los Blancos progressed through to the quarterfinals with relative ease and carried a healthy 4-2 lead to Monaco from the first leg. In the second leg, the tables turned quickly. Although Raul scored the early goal for the visitors, Fernando Morienties, a loanee at Monaco from Madrid combined with Ludovic Giuly to inspire a tremendous comeback. 

Giuly scored twice while Morientes scored a solitary goal and also provided an assist for the Frenchman. Monaco came back from a goal down to win the clash 3-1 and surprisingly progressed to the semifinals. 

8. Celtic 2-1 FC Barcelona (November 2012)

This was one of the most bizarre upsets in the UEFA Champions League till date. Celtic were forced to absorb pressure almost throughout the ninety minutes and enjoyed only 16% ball possession. But they somehow managed to score twice against a formidable FC Barcelona side who eventually made the semifinals. 

https://www.youtube.com/watch?v=qOHKopBdePs

The Scottish champions drew first blood when Victor Wanyama headed home in the 20th-minute mark from a corner. After that Tito Villanova's men bombarded the Celtic defence with incessant attacks and also forced some spectacular saves out of Ben Forster in goal. But it was from Forster's long pass, striker Tony Watt found the winner for Celtic. 

The Blaugrana simply failed to find a way past the Celtic defence and it was only in stoppage time when Lionel Messi scored which resulted in a mere consolation.

7. APOEL Nicosia 1-0 Olympique Lyon (March 2012)

The Cypriot club was on a dream run in the qualifiers to the UEFA Champions League group stage in 2012. If that was not enough, APOEL progressed to the quarterfinals and were drawn against a strong Lyon side. 

Lyon were the most dominant team in France, having won the Ligue 1 title seven times in the last 10 seasons. Therefore Les Gones were the favorites right from the start and even had a 1-0 lead from the first leg.

https://www.youtube.com/watch?v=ZNNKdpS9P3Y

However APOEL's zeal and attitude allowed them to take the attack to the opposition as they found the back of the net in the ninth minute through Gustavo Manduca. The Cypriot outfit held their own throughout the ninety minutes and forced the game into extra time and eventually into penalties. APOEL won the shootout 4-3 after Greek custodian Dionisis Chiotis denied both Alexandre Lacazette and Michel Bastos from the spot.

6. Deportivo de La Coruna 4-0 AC Milan (2004 quarterfinals)

AC Milan were the reigning UEFA Champions League champions from the previous season and they traveled to Spain with a handsome 4-1 first-leg lead. Fans already started to write off Deportivo La Coruna as they were up against a star-studded lineup. However, the Spanish outfit made a great comeback scoring within five minutes of the game through Walter Pandiani. 

https://www.youtube.com/watch?v=w9pE4tUhM4E

The early goal gave the Branquiazuis inspiration to turn the tie around and they led 3-0 at the halftime, courtesy of goals from Juan Carlos Valeron and Albert Luque. Club captain Fran, who started the match on the bench came on in the second half to score the decider. Deportivo made it to the semifinals for the first time in their history by scripting a shocking upset.  

5. FC Barcelona 2-3 CSKA Moscow (November 1992)

Another Barcelona upset by a Russian outfit at the Camp Nou. The Catalans were managed by Johan Cruyff and the Dutchman had a formidable lineup of Pep Guardiola, Ronaldo Koeman, Michael Laudrup and Txiki Begiristain among others. 

https://www.youtube.com/watch?v=iI3497qDW18

The Catalans were held to a 1-1 draw in Moscow in the first leg, with the second leg to be played in Camp Nou. However, CSKA Moscow had different plans. The hosts started strongly and led by 2-1 going into the break. But a second-half blitzkrieg from the Muscovites catapulted them into the lead as the game ended 2-3 in the visitors' favor, resulting in an early exit for Barcelona.

4. Real Madrid 1-4 Ajax (March 2019)

An upset from last season's UEFA Champions League where a young and inexperienced Ajax side showed resilience against 13-time champions Real Madrid. It was supposed to be a feisty round of 16 tie between both the sides, but not many fans predicted the eventual outcome. 

https://www.youtube.com/watch?v=16q4cwzlkWc

Los Blancos had an advantage going into the second leg at Santiago Bernebeu after they defeated Ajax 1-2 away from home and had two away goals in their kitty. However, Ajax showed great character and against all odds, they turned the tie upside down. Hakim Ziyech, Dusan Tadic, David Neres and Lasse Schone scored one each to bag a 1-4 win against the holders and knocking them out in the round of 16. 

3. BATE Borisov 3-1 Bayern Munich (October 2012)

One of those matches were an upset was least expected as Bayern were favourites against hosts BATE Borisov. However, things did not pan out the same way as the Belarusian outfit drew first blood through a goal from Pavlov and had a 1-0 lead at halftime. 

https://www.youtube.com/watch?v=o8lwtchcN2E

It was an intense second half where BATE held their own and doubled the lead via striker Rodionov in the 78th-minute mark. Bayern struggled to find a way past their opponents' low block and it was only in stoppage time when Frack Ribery scored for the visitors and kept them in the game. However, the hosts scored again in the 94th minute through substitute Renan Bressan to finish off the misery. 

Considering the fact that Bayern Munich, managed by Jupp Heynckes, went on to win the Champions League that season and clinched a historic treble, increases the magnitude of this upset. 

2. FC Barcelona 6-1 Paris Saint-Germain (2017 quarterfinals)

The most controversial and infamous comeback in Champions League history. The match was between two evenly matched sides but it was an upset mainly due to the overwhelming odds against the Catalans. 

https://www.youtube.com/watch?v=h4m68r8kWAc

Barcelona were completely outplayed in the first leg by PSG as the Parisians won 4-0 at home. The Catalans knew that it will be an uphill battle to stay in contention. The hosts started strongly with Luis Suarez breaching the PSG defence early on followed by an own goal. Things started looking possible when Messi pulled another one back from the spot after halftime. 

Edinson Cavani's away goal did make things trickier for the hosts but Neymar came up with a stunning free-kick in the 88th minute and followed up with a penalty to make it 5-1. It looked like little too late for Barcelona but Sergio Roberto's stoppage time volley completed the comeback for the Catalans. 

1. Liverpool 3-3 AC Milan (2005 finals)

The Miracle of Istanbul is an upset mainly due to the circumstances that Liverpool were in after the first half. Considering it was a final against a top-notch side, increases the magnitude of the comeback two folds. 

https://www.youtube.com/watch?v=oWdPDofBxl0

It was a fiery start from AC Milan as Paolo Maldini broke the deadlock for the Rossoneri in the first minute of the match. Followed by a first-half brace for Hernan Crespo, as the Reds languished 0-3 at the break. But Rafael Benetiz's men did not lose hope and came back fighting in the second half. 

Hope was restored via Steven Gerrard header early in the second half and that goal gave them hope to push for more. Vladimir Smicer pulled another back with a stunning long ranger followed by an equaliser from Xabi Alonso who missed the spot-kick but tucked in the rebound. The Reds forced extra time and penalties and eventually came out as winners from 0-3 down in the first half.