By Phil McNulty Chief football writer

Benfica 2-1 Man Utd More Champions League photos

Sir Alex Ferguson arrived in Lisbon carrying the weight of Manchester United's glorious past - and left with his Old Trafford future in question.

Benfica and their home at the Stadium of Light hold special places in United's illustrious history.

The late George Best announced his arrival on the world stage in this famous arena, while Benfica were Manchester United's victims when they finally claimed the Holy Grail of the European Cup in 1968.

It was the perfect theatre for United to stage a drama that would salvage their Champions League ambitions and emphasise their status in Europe.

Instead, they gave a display that suggested United are a spent force when set alongside Europe's elite clubs.

Six Champions League group games and one victory - bottom of a group a second-string United side would have strolled through in the past.

A place in the Uefa Cup would have been humiliating for United, but even that meagre consolation is denied to Ferguson.

And most disturbing of all was the manner of a miserable defeat, outplayed by a distinctly average Benfica side even after the lift of Paul Scholes' early goal.

Frustrated Rooney could not lift dismal United

Ferguson's teams of the past would have revelled in this night of brinksmanship - this time they shrank from the responsibility and raised serious questions about the manager's continued motivational powers.

No pattern. No shape. No threat. No spark. No quality. No Champions League place. No European place.

Even Wayne Rooney and Ruud van Nistelrooy could not ignite a dreadful display - so maybe outcast ex-captain Roy Keane was right after all.

And if Ferguson employed his famous "hair-dryer" in the face of his players after a stunning first-half capitulation, its lack of effect suggests it may need to be traded in for a newer model.

The same may now apply to the manager.

Ferguson, for arguably the first time in all his years at Old Trafford, looked a helpless, shell-shocked and beaten figure in the dug-out as his once all-powerful side failed to lay a glove on Benfica with their season's biggest target on the line.

The United of times past would have risen off the canvas and delivered the knockout blow. Instead the ageing champions were slow, short on ideas and devoid of inspiration.

Ferguson turned to his golden generation to pull United out of trouble in Lisbon, but the old guard of Paul Scholes, Ryan Giggs and Gary Neville failed to deliver.

This football fall-out will reverberate all the way to Tampa, where this defeat compounds a dreadful start to the Glazer era at Old Trafford.

Benfica's victory has cost United millions in European cash - but the damage to the club and Ferguson's credibility may be even more serious.

The warning signs have been posted around Old Trafford all season, from misery at Middlesbrough to defeat in Lille.

United look past their best - and now it is right to question whether Ferguson has suffered a similar fate.

Chelsea have a firm grip on the Premiership, leaving United with what they will regard as the crumbs of the FA and Carling Cup.

If Ferguson stays, and make no mistake his position must now be questioned, how does he revamp a team that now relies on the brilliant Rooney to an over-exaggerated extent?

Van Nistelrooy is not the predator of old and Scholes and Giggs are fading.

And could it be that even Rooney himself has joined United at the wrong time?

Ferdinand reflects on United's defeat

United, on this season's evidence, look light years away from being serious European contenders and that will not sit easily with the world's greatest young talent.

Ferguson will fight on, but can he even attract the players he needs to replace the familiar faces?

Chelsea's millions pose the greatest threat - but Ferguson can hardly make a footballing case for a club dumped out of the Champions League at the group stage.

Five British clubs entered the group stage and only United failed to advance. This stark fact says it all.

The Scot is famous for his fierce competitive spirit, but he may not get the time to fashion another United side to challenge for the Champions League.

He has enjoyed many glorious nights - and no-one should ever write him off - but Ferguson is at crisis point and this will rank as one of his worst lows.

His team betrayed him in Lisbon and United are now reduced to Europe's ranks, a painful place for this famous club and all-time great manager to be.

And that is why this desperate performance in Lisbon leaves Ferguson facing a fight for his managerial career.