Barcelona's Champions League campaign feels all but over as they head to Paris Saint-Germain nursing a 4-1 last-16 deficit.

Kylian Mbappe made merry at Camp Nou last month, netting a brilliant hat-trick after Lionel Messi gave the hosts a first-half lead.

The fact the defeat came on their own patch makes Barca's hopes even more remote, but they've been on both sides of incredible recent Champions League comebacks – most famously in this very fixture.

Here, we look at some of the nights in Europe's top competition where logic left town.

2019: Liverpool 4-0 Barcelona (4-3 on aggregate)

Jurgen Klopp's Liverpool had been well beaten at Camp Nou, with the 3-0 scoreline flattering Barcelona but making the Catalans clear favourites to complete their semi-final task on Merseyside.

Liverpool were without injured forwards Mohamed Salah and Roberto Firmino for the second leg, yet two goals each from Divock Origi and Georginio Wijnaldum saw the hosts defy the odds in sensational style.

They were Origi's first goals in the competition, while only 122 seconds separated Wijnaldum's pair in a pivotal period that left Anfield rocking.

Origi had the final word thanks to Trent Alexander-Arnold's quick thinking from a 79th-minute corner.

It meant a Barcelona side boasting Messi – who was involved in all of Barca's eight attempts on goal with five shots and three key passes - and former Liverpool stars Philippe Coutinho and Luis Suarez were left devastated, while Klopp's men celebrated reaching the Madrid final.

2019: Real Madrid 1-4 Ajax (5-3 on aggregate)

Despite an impressive display in their 2-1 first-leg defeat, few thought Ajax could turn things around at the Santiago Bernabeu. Madrid's Sergio Ramos certainly did not - he earned a first-leg booking to avoid the risk of a quarter-final ban, receiving an extra-game suspension from UEFA in the process.

In the absence of their captain, Madrid capitulated against a fearless and thrilling Ajax. Hakim Ziyech and David Neres put the visitors 2-0 up after only 18 minutes and it was 3-0 just after the hour thanks to the inspired Dusan Tadic.

Marco Asensio got a goal back, but Lasse Schone's free-kick beat Thibaut Courtois and sent Madrid crashing out on the back of their heaviest margin of defeat in a European knockout game. It was the first time Madrid had ever been knocked out after winning the first leg of a Champions League tie, while Ajax would themselves be stung by a comeback in the semi-finals.

2019: Ajax 2-3 Tottenham (3-3 agg)

Ajax looked certain finalists when they extended their 1-0 first-leg lead to 3-0 on aggregate in Amsterdam, thanks to first-half goals from Matthijs de Ligt and Ziyech.

Mauricio Pochettino's Spurs took inspiration from Liverpool's stunning fightback against Barcelona 24 hours earlier, though, and Lucas Moura stepped up to emerge as their hero.

The Brazilian winger was thrust into a central attacking role and scored an improbable hat-trick – just the fifth time the feat had been accomplished in a Champions League semi-final - in the second half, the vital third goal coming deep into stoppage time, as Spurs won on away goals.

2018: Roma 3-0 Barcelona (4-4 agg)

Barcelona were stunned in the Italian capital as Roma completed one of the most unlikely quarter-final turnarounds.

Eusebio Di Francesco's side came back from a 4-1 first-leg deficit to progress to the last four on away goals after a thrilling 3-0 win in front of their home fans.

Edin Dzeko, Daniele De Rossi and Kostas Manolas secured the 4-4 aggregate draw and sent the Stadio Olimpico into raptures, as Barca fell to pieces.

2017: Barcelona 6-1 Paris Saint-Germain (6-5 agg)

Before being humbled by Roma and Liverpool, Barcelona pulled off an astonishing Champions League comeback of their own - the greatest so far in terms of the deficit overhauled and one that PSG fans will still shudder to be reminded of this week

Trailing 4-0 from the first leg of their last-16 tie with PSG, Suarez and Messi scored either side of a Layvin Kurzawa own goal, only for Edinson Cavani to grab what was expected to be the decisive away goal for the visitors.

However, two quickfire Neymar goals against his future club – the second a highly controversial penalty after Suarez took a tumble – levelled the tie at 5-5.

Then, in the fifth minute of stoppage time, Sergi Roberto struck to create a slice of Champions League history – no side had ever turned around a four-goal first-leg deficit before.

2004: Deportivo La Coruna 4-0 Milan (5-4 agg)

Deportivo were among Spain's major forces just after the turn of the century and one of their finest moments in Europe came in April 2004 when, despite being 4-1 down from the first leg of their Champions League quarter-final with Milan, they stunned the Rossoneri at the Riazor.

Walter Pandiani, Juan Carlos Valeron and Albert Luque had Depor ahead on away goals before half-time, with veteran Fran Gonzalez scoring the fourth to make sure of their passage.

Depor were eliminated by eventual winners Porto in the semi-finals, but this comeback stood as arguably the very best in Champions League history until Barca went one better.

2000: Barcelona 5-1 Chelsea (aet, 6-4 agg)

Another time Barcelona overturned the odds.

A 3-1 first-leg loss at Stamford Bridge – having trailed 3-0 – had Barca in danger of being on the wrong end of a major Champions League upset prior to Chelsea's Roman Abramovich era, but in the return match the Catalan giants showed their true class.

Tore Andre Flo's 60th-minute goal was sending Chelsea through despite Rivaldo and Luis Figo scoring before the break, but Dani Garcia headed home in the 83rd-minute to force extra time.

Rivaldo atoned for an earlier missed penalty by converting from the spot after Celestine Babayaro was sent off and Patrick Kluivert finished the game off, crushing Chelsea's dreams.