For Manchester United the old and once thrilling adventure of European football has once again turned into a nightmare of missed opportunity, a rebuke to the idea that pulverising form in the Premiership will ever be a guarantee of success against teams where defence is foundation not an afterthought.

For Manchester United the old and once thrilling adventure of European football has once again turned into a nightmare of missed opportunity, a rebuke to the idea that pulverising form in the Premiership will ever be a guarantee of success against teams where defence is foundation not an afterthought.

United went the way of Arsenal, their recently so exalted rivals, in a moment of terrible breakdown here last night. They were pushed into the margins of the Champions' League by another chilling mistake by goalkeeper Roy Carroll, but he was the man conveniently placed to take the blame.

When he spilled a shot from Milan's Clarence Seedorf into the path of Hernan Crespo, you knew where the shadow of guilt would linger. But the reason United's position in Europe is so fragile nowgoes deeper than a failure to find an adequate replacement for Peter Schmeichel.

They brought on Ruud van Nistelrooy, their great force before injury struck him down at the heart of United's season, but it seemed too late: by then we suspected the damage had already been done.

Before that, some of the football was beautifully electric but it was a critical view that was surely not too rapturously endorsed by Sir Alex Ferguson when he set about reminding his team about what really matters at the top of the European game.

He did it at half-time with the pained expression of a football man locked into one of the oldest truths of the game. It was that one which says the higher you go the greater the need for that cutting edge which separates the big winners from the merely talented. At the receiving end were Quinton Fortune and, of all people, Paul Scholes. Both had glorious chances to make the point that while Milan weaved the more intricate patterns, and had most of the ball, it was United who produced the greater bite ... and maybe had their best chance so far this challenging season to move beyond the shadow of Jose Mourinho's Chelsea.

Unfortunately the gap between promise and reality was cruelly underlined for the United manager with the news that Chelsea, the team who were supposed to be falling apart, had stolen the lead at the Nou Camp against Barcelona - and the extraordinary fact that Milan were not as they should have been, which is to say two goals down. That would have been the case if Scholes had done something he has trademarked for what sometimes seems for ever, breaking late into the box with perfect timing and a killing instinct.

Fortune sent in the ball and Scholes arrived upon it just as his scriptwriter generally insists. But this time Scholes, from just 12 yards out, fired wide.

The language of Ferguson and most of Old Trafford mingled shock and despair, understandably enough. When you are playing a team whose defence contains names like Alessandro Nesta and Paolo Maldini the trigger always has to be pulled. You miss the chance to do so, and you know you might have to spend quite a time with your regrets. Fortune soon joined Scholes in the terrain of what might have been and for Ferguson the haunting fear was that his greatest chance to reconquer Europe in six years might have come and gone.

That worry became a near certainty when Carroll, just another goalkeeper floundering in the daunting legacy of Schmeichel, gave Milan their chance to profit from United's failure to take chances that seemed likely to flow inevitably from the razored pace of Cristiano Ronaldo and several moments of resurrected brilliance by Ryan Giggs.

Ferguson had believed in the vibrant form of team. He thought Wayne Rooney would be able to carry the burden effectively until Van Nistelrooy was brought on late and maybe triumphantly. But the burning form in England, the growing sense that his team could take over again in the face of such a usurping force as Chelsea, suddenly looked so much dreaming. Milan came from that other world of stealth and, ultimately, winning football.