Five things we learned from United's victory
1. MANCHESTER UNITED CAN STILL DO COMEBACKS
Along Old Trafford's endless corridors, the televisions were broadcasting from Manchester United's considerable archives of great comebacks. There was the Bryan Robson-inspired victory over Barcelona in 1984 that was the last time they had overturned a two-goal first-leg deficit. There was Steve Bruce's late, late header against Sheffield Wednesday in 1993 and, of course, the moment that defined the Ferguson era – Ole Gunnar Solskjaer's winner against Bayern Munich in 1999.
It would be laughable to compare Olympiakos with Bayern but this was a reminder of what Manchester United are about. It was probably not necessary for United to go through last night for David Moyes to survive but it was imperative they performed. Here, they did both.
2. VALENCIA IS A TOUGH PLAYER, RAFAEL IS A DANGEROUS ONE
Before kick-off, United captain Patrice Evra urged his players to "give everything for the shirt". It may have been a cliché but Antonio Valencia responded with the kind of display Bryan Robson would have recognised.
Captain Marvel would probably have also recognised the boxer's bruise that almost closed the midfielder's eye. The clash with Joel Campbell was early enough and serious enough for the Ecuadorian to be forced off. Instead, within minutes, he was tackling back against the on-loan Arsenal striker and then racing down the right flank only to be brought down by Ivan Marcano.
Rafael da Silva made a sizeable contribution to Manchester United's elimination from the Champions League four years ago with his dismissal against Bayern Munich and it was his handball that gave Liverpool the first of their three penalties on Sunday. Again he was loose early on and a better team than Olympiakos would have exploited it.
3. YOU DON'T HAVE TO LIKE A MANAGER TO PLAY FOR HIM
Mike Brearley, who captained England to three Ashes triumphs, wrote a manual for sports leadership, called 'The Art of Captaincy'. In it, he exploded the theory that successful teams all got along in the dressing-room. Brearley argued that dressing-room tensions were actually creative as people sought to prove a point.
If the stories detailing the rifts between Moyes and Ryan Giggs are correct then his performance last night, full of all the vision and cunning that makes him a great footballer at 40, proved Brearley right. This would be par for Moyes' course at Old Trafford. He has, after all, agreed a five-year contract with Wayne Rooney, a man he once sued for libel.
4. OLYMPIAKOS ARE NOT THAT GOOD
They were not, to Roy Keane's evident disgust, all that good when winning 2-0 in Athens. They were, admittedly, far better than Galatasaray had been at Chelsea on Tuesday but it was only when Robin van Persie scored United's third that Olympiakos began really to threaten.
Had United been up against one of the big beasts of European football, it is unlikely the night would have burned quite so brightly for Moyes and Van Persie.
Olympiakos have not travelled well, even in this season's Champions League, and this was their 12th straight defeat in England. But for David de Gea's brilliant double save before half-time, they might have held on.
However, the problem with being champions of a very weak league is that you are very seldom stretched. Here they were and they broke early.
5. UNITED DESERVE APPLAUSE BUT NOT AN OVATION
For once, Manchester United played at Old Trafford as if it were their home ground and they have progressed further in the competition than their great rivals at the Etihad.
Nevertheless, they have only reached the quarter-finals of the European Cup – which is precisely what they budget for at Old Trafford. They could, like Liverpool in 2005 and Chelsea in 2012, win the European Cup without finishing in the top four. Somehow, you doubt it. (© Independent News Service)