Much has changed in European football in the past five years – and few clubs illustrate that greater than fallen giants Barcelona.
On this day in 2017, Barca were thrashing Paris Saint-Germain 6-1 in the most remarkable Champions League turnaround ever, becoming the only side in the competition's history to overturn a four-goal first-leg deficit.
Now, Neymar and Lionel Messi – the two stars of that Blaugrana side – are preparing to play Real Madrid as PSG players.
Meanwhile, Barca are not even in the Champions League knockout stages, instead facing Galatasaray in the Europa League last 16 while battling to return to UEFA's flagship competition next season.
Indeed, Barca's recent European past has found them on the wrong end of epic Champions League comebacks, but that PSG classic still ranks among the tournament's greatest two-legged recoveries – remembered by Stats Perform here...
2019: Liverpool 4-0 Barcelona (4-3 on aggregate)
One of a couple of examples Barca fans will not remember so fondly, Jurgen Klopp's Liverpool had been well beaten at Camp Nou, with the 3-0 scoreline flattering the Catalans but making them clear favourites to complete their semi-final task at Anfield.
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.
Origi had the final word thanks to Trent Alexander-Arnold's quick thinking from a 79th-minute corner.
It meant a Barca side boasting Messi and former Liverpool stars Philippe Coutinho and Luis Suarez were left devastated, while Klopp's men celebrated reaching the final, where they would win a sixth title.
2019: Ajax 2-3 Tottenham (3-3 agg)
The night after Liverpool's win, Ajax looked certain to join the Reds in the final when they extended their 1-0 first-leg lead to 3-0 in Amsterdam with first-half goals from Matthijs de Ligt and Ziyech.
Mauricio Pochettino's Tottenham took inspiration from Liverpool's stunning fightback 24 hours earlier, though, and Lucas Moura stepped up to emerge as their hero.
The Brazilian forward scored an improbable hat-trick 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 – another that benefited from an away goals rule that has since been scrapped.
Eusebio Di Francesco's side came back from a 4-1 first-leg deficit to progress to the last four 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)
Those humblings at the hands of Roma and Liverpool make for painful memories for those of a Blaugrana persuasion, but this remains the ultimate 'Remontada'.
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 – the second a highly controversial penalty after an apparent Suarez dive – brought it back to 5-5, meaning Barca needed just one more.
Then, in the fifth minute of stoppage time, Sergi Roberto struck from Neymar's cross to create Champions League history.
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)
Barca already had a history of Champions League fightbacks.
A 3-1 first-leg loss at Stamford Bridge – having trailed 3-0 – had the Blaugrana 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 seven minutes from the end of regulation 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.