It was an act of defiance when Busby took United into the European Cup of 1956-57, the action of an unbending man who saw the club's destiny on the Continent. The Football League, which had stopped Chelsea entering the year before, was implacably opposed. The grounds for its objections? It feared United might be unable to fulfill their domestic fixtures with the burden of extra matches.
Old Trafford and Europe were intertwined from that moment, inextricably so when, 17 months after their first match, against Anderlecht of Belgium, Busby's team died on the runway of Munich Airport. Tragedy had pushed Europe into the folklore of the club far more firmly than any number of trophies could. Since then any fixture against Continental opposition has carried undertones of February 6, 1958.
Which is not to say that triumph has not risen above the memory of Munich, most notably the European Cup win of 1968.
The greatest of them all was the 5-1 destruction of Benfica in the Stadium of Light, a place where the Portuguese champions had never been beaten in Europe before - but Old Trafford, too, has played host to matches laced with the extraordinary.
These are four nights to remember, from the 1950s, 60s, 70s and 80s. As for the 90s, Borussia Dortmund tonight would do nicely...
European Cup semi-final first leg (8 May, 1958): Manchester United 2 Milan 1 (United lost 5-2 on aggregate).
Eight players died at Munich and two others never played again, so it was a desperately weakened team that appeared in the first match in Europe after the tragedy, one that was further handicapped by England's insensitive decision to take Bobby Charlton on a pre-World Cup tour.
Tears but little hope accompanied the red shirts on to the field five days after they had lost the FA Cup final, and things looked even more gloomy when Milan took the lead after 24 minutes. United were being run ragged.
Then, five minutes from half-time, the present coach of the Italian national team, Cesare Maldini, misplaced a back-pass and Dennis Viollet changed the mood with an equaliser. United tore at Milan, Ernie Taylor scoring the winner from the penalty spot 11 minutes from time after Viollet had been fouled by Maldini. "I have never seen a crowd set alight with a flame of victory as this," Terence Elliott wrote in the Daily Express.
The second leg six days later proved how shallow the well of sympathy can be. The Italian crowd pelted the United players with vegetables as they took the field and Milan, mindful of their treatment at Old Trafford, got their revenge. "Most of us were glad to escape with a 4-0 defeat," Bill Foulkes recalled. "We had run out of emotional steam."
European Cup quarter-final first leg (2 February, 1966): Manchester United 3 Benfica 2 (United won 8-3 on aggregate).
Trying to describe everything that happened in this match, one reporter wrote, would be "like trying to remember an evening with Oscar Wilde, so many were the shafts of wit and poetry".
This was the Manchester United side that most people regard as Busby's best after Munich. Bobby Charlton was in his pomp, Denis Law was not suffering from the injuries that would force his withdrawal from the European Cup winning team two years later, and George Best was just beginning to add maturity to his prodigious talent.
Benfica, too, were multi-gifted, providing the bulk of the Portuguese national team who would reach the semi-finals of the World Cup five months later. Most of all, they had Eusebio, a player then regarded as second only to Pele.
Eusebio, languid looking but sharp as a needle, made both of Benfica's goals, putting them 1-0 ahead on the half hour and reducing United's advantage after David Herd, Law and Foulkes had given the home team a 3-1 lead. United also hit the bar twice while Eusebio crashed a shot just wide in the closing seconds.
A frantic, thrilling match that apparently left United with little hope for the return. Best would change all that with an extraordinary second leg...
European Cup-Winners' Cup second round second leg (2 November, 1977): Manchester United 5 Porto 2 (United lost 6-5 on aggregate).
Amid any list of great matches, a place should be found for glorious failure, and few were as worthy of mention as this. Porto arrived haughtily at Old Trafford, fortified with a 4-0 lead, and left it a dishevelled mess, fortunate to reach the third round.
In the first leg a centre-forward called Duda had tortured the United defence, scoring a hat-trick in 54 minutes, while Jimmy Nicholl twice had to clear off the line. "It's going to be hard, very hard," Dave Sexton, the United manager, said, "but I refuse to believe it's impossible."
Sexton would later be dismissed for being too cautious, but there was little inhibition in the home leg where United attempted the impossible and nearly achieved it. Steve Coppell gave them the lead after eight minutes and, even though Porto equalised soon afterwards, they continued to pummel the visitors, going ahead 4-1.
Two more, just two, and with the Porto defence in a terrible state anything could have happened until Seninho ended all hope with a dribble past Martin Buchan and Arthur Albiston in the 84th minute. United were not finished, Stuart Pearson forcing Murca into his second own goal of the game. "We were mugs for being caught out with two breakaway goals," Pearson said.
European Cup-Winners' Cup quarter-final second leg (21 March, 1984): Manchester United 3 Barcelona 0 (United won 3-2 on aggregate).
This display was described by Ron Atkinson as the finest by a United side while he was manager. Down 2-0 from the first leg against a Barcelona side that included Diego Maradona and Bernd Schuster, United appeared to have only the lucky puncher's chance, with the proviso that the slugger usually leaves himself open to counter-attack.
What had been buried in the debris of a disappointing first leg was that Bryan Robson had squandered two chances, opportunities that he remembered even if others did not. "I felt responsible for the defeat," he said. "Big games are all about putting the ball into the net."
Robson played like a man possessed at Old Trafford, imposing his presence on Schuster while Remi Moses man-marked Maradona and Ray Wilkins had one of his finest matches in a red shirt. Up front, Norman Whiteside won virtually every ball in the air.
Ahead after 24 minutes thanks to Robson's header, United went ahead in the tie with two goals in two minutes early in the second half. Robson made it 2-0, then Frank Stapleton got the third. Schuster went close and Maradona had a last-minute shot saved by Gary Bailey, but United made it to their seventh European semi-final.Reuse content