Arsenal will need to overcome a 4-0 deficit when they face Milan at Emirates Stadium on Tuesday night if they are to continue their Champions League adventure.
Here, TEAMtalk looks at six memorable European comebacks which may give them hope - particularly the first two.
Liverpool 3 AC Milan 3 (Liverpool won 3-2 on penalties, Champions League final, May 2005)
Liverpool beat AC Milan in a penalty shoot-out to win the Champions League after sensationally coming from three goals down at half-time. Paolo Maldini gave Milan a first-minute lead, and two goals from Hernan Crespo put them in a seemingly unassailable position at the interval. Reds captain Steven Gerrard gave Liverpool hope, and Vladimir Smicer and Xabi Alonso levelled in a seven-minute spell. Jerzy Dudek then saved from Andrea Pirlo and Andriy Shevchenko in the shoot-out to clinch a stunning victory.
Deportivo La Coruna 4 AC Milan 0 (Champions League quarter-final, April 2004)
Deportivo left the San Siro after the first leg on the end of a 4-1 defeat facing the task of overhauling a three-goal deficit against an Italian defence including Maldini and Alessandro Nesta. Walter Pandiani's early goal was added to by Juan Carlos Valeron's header half an hour later as the Spanish side started to believe. Just two minutes before half-time Albert Luque held off Nesta before smashing the ball into the roof of the net to put the home side ahead on aggregate. Veteran substitute Fran stunned the Rossoneri when he sealed the amazing comeback with a fourth goal 15 minutes from time.
Man Utd 2 Bayern Munich 1 (European Cup final, Nou Camp, May 1999)
United trailed for nearly the entire game after falling behind to Mario Basler's sixth-minute free-kick. But, in the most amazing finish in the competition's history, United turned the game on its head. Substitute Teddy Sheringham equalised with a shot on the turn from eight yards and extra-time beckoned. But United had other ideas and, when David Beckham's corner was flicked on by Sheringham, fellow substitute Ole Gunnar Solskjaer rifled the ball into the roof of the net as United became the first club to win the treble of European Cup, Premier League title and FA Cup.
Dinamo Zagreb 1 Lyon 7 (Champions League Group D, December 2011)
Lyon routed 10-man Dinamo Zagreb and completed a remarkable nine-goal swing to qualify for the last 16 of this season's competition ahead of Ajax. With the Dutch side losing to group winners Real Madrid, Lyon had a mathematical chance of going through but were seven adrift on goal difference. Real's 3-0 win in Amsterdam did some of the work but a stunning six-goal showing in the second period against Dinamo, who had led 1-0, was decisive. Bafetimbi Gomis scored a seven-minute hat-trick, while Maxime Gonalons, Lisandro Lopez and Jimmy Briand also found the net.
Middlesbrough 4 Basle 1 (UEFA Cup quarter-final, April 2006)
Boro trailed 2-0 after the UEFA Cup quarter-final first leg in Switzerland and no-one gave Steve McClaren's side a chance of making it through - especially when the visitors took a 23rd-minute lead through Eduardo. Mark Viduka equalised before half-time and his second in the 57th minute gave the Teessiders the belief they needed to push on. Jimmy Floyd Hasselbaink scored Boro's third to put them in the ascendancy and, with four strikers on the pitch at the end, substitute Massimo Maccarone fired in a 90th-minute winner to seal a 4-3 aggregate victory.
Middlesbrough 4 Steaua Bucharest 2 (UEFA Cup semi-final April 2006)
For the second time in three weeks Boro scored four goals in a match to snatch a remarkable victory, this time beating Steaua Bucharest 4-2 to progress to the UEFA Cup final 4-3 on aggregate. A goal down from the first leg, Boro's hopes looked to have ended when Nicolae Dica and Dorin Goian put the visitors 2-0 up on the night inside 24 minutes. However, substitute Maccarone pulled one back before half-time before Viduka, Chris Riggott and Maccarone - in the 89th minute - led McClaren's side to the final.
Any reproduction, publication or redistribution of this material without the written agreement of 365 Media Group is strictly forbidden.