The double winners' famous undefeated European home record, forged by the doomed generation of Duncan Edwards and Tommy Taylor, gilded in the era of George Best, Denis Law and Bobby Charlton, is no more. Fifty-six teams had come and attempted to spoil it, all had failed. They included the greats - Di Stefano and Real Madrid, Maradona and Barcelona. All had failed, now Fenerbahce, unheralded and unfancied, have triumphed.
The Turkish champions won through a goal from Elvir Bolic, a Bosnian, who scored with 13 minutes remaining. The goal inspired a previously insipid United into pouring forward but nothing, not even the introduction of Peter Schmeichel into the attack, could save them.
Now they must take four points from their last two Champions' League games - at home to Juventus and away to Rapid Vienna - to be sure of qualifying for the quarter-finals. The one consolation is that, should they finish level with Fenerbahce, United will progress by virtue of their scoring two goals in Istanbul to Bolic's one.
The defeat caps a terrible 11 days for United. In that time they have been humbled 5-0 by Newcastle and 6-3 by Southampton. It is not the way Alex Ferguson would have wished to approach the celebration of his decade at the Old Trafford helm.
The anniversary is next week and Ferguson reflected last night: "It is an ironic life. You prepare to celebrate 10 years at a club and suffer their first defeat in European football. Tonight [the press conference] is a struggle.
"Our tempo was disappointing, the speed of our passing and penetration. It is a night we won't forget - we won't be allowed to. Now we have to win our games. We need 10 points but nine might be enough."
Sebastiao Lazaroni, Fenerbahce's Brazilian manager, said: "I don't think it was a good game but it was a historic one. We are still alive."
Ferguson insisted United "didn't deserve to lose" but nor did they deserve to win. They appeared more disturbed by their recent results than Ferguson was prepared to accept. They looked inhibited, their movements and passing were deliberate rather than instinctive. Paradoxically they also appeared, at times, to be complacent. This was a team they had beaten comfortably in their own backyard.
Not that the Turks looked any better. They had one effort in the first half - the best chance of the period - and Kemalettin Senturk volleyed it over the bar.
United had been equally wayward. Jordi Cruyff did, at least, test the goalkeeper with a tightly-angled shot but Eric Cantona wasted a good chance when put through by Nicky Butt.
The game picked up after the interval as both sides re-emerged with a sense of adventure in their hearts. The Turks, aware that they needed a win even more than United, were first to show, with Emil Kostadinov just failing to divert Bolic's fierce cross under the bar.
United responded with Karel Poborsky releasing Nicky Butt beyond the defence. Barely had he controlled the ball, however, than Rustu Recber was upon him. The goalkeeper saved with his feet and Cruyff failed to convert the rebound.
United replaced him with Paul Scholes and almost earned an instant - though accidental - success as his mis-hit cross drifted onto the crossbar.
A minute later calamity struck. Bolic drifted free on the left and, as David May came in, shot. The ball skimmed off May and dipped over Schmeichel. United were stunned, Old Trafford, except for 460 exulting Turks, silent. They soon found their voice, but not before Kostadinov had glanced a header against the post.
United now launched attack upon attack but there was a air of panic about them. Even David Beckham, their best player on the night, fell prey to it.
United's young men are learning all the time but their test last night was an unusually searching one. As well as the customary European lesson, they were facing an examination of character. They have passed many tests, and will pass many more, but last night they failed.
Manchester United (4-3-3): Schmeichel; G Neville (P Neville, 82), Johnsen, Pallister, Irwin; Beckham, Keane, Butt; Poborsky (Solskjaer, 67), Cantona, Cruyff (Scholes, 67). Substitutes not used: McClair, Van der Gouw (gk).
Fenerbahce (4-4-2): Rustu; Ilker, Okechukwu, Saffet, Erol; Hogh (Bulent, 78), Kemalettin, Okocha, Tuncay (Mustafa, 72); Bolic (Tarik, 81), Kostadinov. Substitutes not used: Halil Ibrahim, Murat (gk).
Referee: M van der Ende (Netherlands).