What's the greatest Scottish comeback in European competition?
"Crazy and unbelievable", "the best match I have ever played in my life", "a historic achievement that will be remembered forever".
These are just some of the reactions to Barcelona's astonishing Champions League comeback from a 4-0 first-leg defeat by Paris St-Germain.
The Catalans turned the tie on its head - and scrambled the senses of fans worldwide - by winning the return leg 6-1 at the Nou Camp. They were 5-3 down on aggregate in the 88th minute.
Social media sites were ablaze with comment but one Tweet, from Dunfermline Athletic's official account, stood out.
".@FCBarcelona... congratulations guys.... fancy a friendly to say sorry for taking our record," read the tongue-in-cheek invite from the Scottish Championship club.
So, what is the record the Fifers are referring to, and is it the finest comeback involving a Scottish team in Europe?
Dunfermline 6-2 Valencia, 1962 Fairs Cup (6-6 on aggregate, Valencia won deciding third match 1-0)
Valencia won the 1961-62 Fairs Cup by beating Barcelona 7-3 on aggregate. The following season the holders journeyed to East End Park on an icy night just before Christmas boasting a 4-0 lead from the first leg.
Manager Jock Stein, less than three years before his appointment at Celtic, had urged his Dunfermline players to attack from the first whistle.
And the team, who had beaten Everton in the previous round, rattled the Spaniards with three goals within 17 minutes.
The Fifers then conceded a goal but scored two more to peg the match at 5-5 on aggregate at half-time.
Centre-half Jim MacLean deflected a shot into his own net to dampen the hosts' hopes before Alex Smith made it 6-2 on the night, 6-6 on aggregate.
In the days before the away goals rule, the tie was decided in a third game in Lisbon, which Valencia won 1-0 to reach the quarter-finals. The Spaniards went on to retain the trophy with a 4-1 aggregate victory over Dinamo Zagreb.
Kilmarnock 5-1 Eintracht Frankfurt, 1964 Fairs Cup (Killie won 5-4 on aggregate)
Arguably, Kilmarnock's feat against Eintracht Frankfurt in their first year in European football trumps the Pars' claim.
The Germans, who had lost 7-3 to Real Madrid in the famous 1960 European Cup final at Hampden, were 3-0 up from the first leg.
And they looked to have killed off any Killie hopes of progressing to round two of the Fairs Cup when they scored within two minutes at Rugby Park to make it 4-0.
But the 14,930 fans roared the hosts forward and Ronnie Hamilton netted twice with Brian McIlroy, James McFadzean and John McInally also scoring to seal a sensational comeback.
Has anything topped those games?
Celtic came close to over-turning a 5-0 first-leg defeat by Artmedia Bratislava in 2005, winning the second leg 4-0. But can anything better those games involving Killie and the Pars?
Use the comments section to provide us with suggestions and share your memories of great European nights involving your club.