Chelsea face a gargantuan task if they are to retain their Champions League crown after a 3-1 first-leg defeat at home to Real Madrid in the quarte-finals.
Karim Benzema scored a hat-trick for Madrid, which puts the Spanish side firmly in control of the tie despite Kai Havertz's effort.
However, there is still hope for Chelsea as there are several examples of two-goal deficits from Champions League first-leg ties having been overturned in the past.
Indeed, Chelsea themselves have been involved in two such dramatic comebacks...
Have Chelsea ever overturned a two-goal first-leg deficit?
Chelsea won the Champions League for the first time in 2011/12, and in getting there they showed tremendous spirit to prevail past Napoli in the round of 16.
Juan Mata put Chelsea in front in the first leg in Italy, but Napoli ended up winning 3-1 as Ezequiel Lavezzi scored a brace and Edinson Cavani also netted.
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However, Chelsea won 4-1 in the second leg. Didier Drogba opened the scoring before John Terry made it 2-0 on the night. Gokhan Inler scored for Napoli but a penalty from Frank Lampard sent the game into extra-time, where Branislav Ivanovic was the hero as he got the decisive goal.
In the quarter-finals in 2013-14, Chelsea also managed to overturn a two-goal first-leg deficit against Paris Saint-Germain.
PSG won the first leg 3-1 in France, with Lavezzi again netting against the Blues. Eden Hazard equalised for Chelsea but David Luiz scored an own-goal as PSG went in front before Javier Pastore doubled the lead.
In the return fixture, Chelsea won 2-0 on the night and progressed on away goals as Andre Schurrle and later Demba Ba scored. Chelsea were knocked out by Atletico Madrid in the semi-finals that season.
What is the Champions League's biggest second-leg comeback?
The Champions League's biggest second-leg comeback and one of the most memorable results in the history of football came in the 2016/17 campaign when Barcelona stunned PSG.
PSG won 4-0 in the first leg as Angel Di Maria got a brace, while Julian Draxler and Cavani also struck.
Remarkably, Barcelona won 6-1 in a second leg now known as "La Remontada", with Sergi Roberto getting the decisive goal in the fifth minute of stoppage time, sending the Camp Nou into raptures.
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There have also been four instances of teams coming back from being three goals down after the first leg.
In the 2018/19 semifinals, Barcelona were the victims, with Liverpool winning the second leg 4-0 after a 3-0 victory for the Blaugrana in Catalonia.
Prior to that, in the 2017/18 campaign, Roma lost 4-1 to Barcelona in the first leg of the quarter-finals but won the second leg 3-0 and ended up progressing on away goals.
In the 2003/04 quarter-finals, AC Milan beat Deportivo La Coruna 4-1 in the first leg but lost the second leg 4-0. Ten years previous, Linfield won 3-0 against Copenhagen in the first leg of their first-round tie, but lost 4-0 after extra-time in the second leg.
How many two-goal deficits have been overturned in Champions League history?
Outside of those aforementioned 3+ goal anomalies, under its current guise (since 1992), there have been 13 occasions in the Champions League when a team has managed to overturn a first-leg deficit of exactly two goals.
| Season | Round | First-leg result | Second-leg result |
| 2018/19 | Round of 16 | Atletico Madrid 2-0 Juventus | Juventus 3-0 Atletico Madrid |
| 2018/19 | Round of 16 | Manchester United 0-2 PSG | PSG 1-3 Manchester United |
| 2016/17 | Round of 16 | Manchester City 5-3 Monaco | Monaco 3-1 Manchester City |
| 2015/16 | Quarter-finals | Wolfsburg 2-0 Real Madrid | Real Madrid 3-0 Wolfsburg |
| 2014/15 | Quarter-finals | Porto 3-1 Bayern Munich | Bayern Munich 6-1 Porto |
| 2013/14 | Round of 16 | Olympiacos 2-0 Manchester United | Manchester United 3-0 Olympiacos |
| 2013/14 | Quarter-finals | PSG 3-1 Chelsea | Chelsea 2-0 PSG |
| 2012/13 | Round of 16 | AC Milan 2-0 Barcelona | Barcelona 4-0 AC Milan |
| 2011/12 | Round of 16 | Napoli 3-1 Chelsea | Chelsea 4-1 Napoli (a.e.t.) |
| 2003/04 | Quarter-finals | Real Madrid 4-2 Monaco | Monaco 3-1 Real Madrid |
| 1999/00 | Quarter-finals | Chelsea 3-1 Barcelona | Barcelona 5-1 Chelsea (a.e.t.) |
| 1993/94 | First Round | Dynamo Kiev 3-1 Barcelona | Barcelona 4-1 Dynamo Kiev |
| 1993/94 | First Round | Rosenborg 3-1 Austria Vienna | Austria Vienna 4-1 Rosenborg |