James Lawton: Gunners' aura of invincibility replaced by foreboding

Chastising Roy Keane over his old disparagement of the FA Cup seems particularly irrelevant today. When he said it was no more than a consolation prize, he had a blockbusting autobiography to sell and Arsenal didn't stand like some great Californian Redwood shutting out the light at Old Trafford.

Now, with Arsenal chopped down, at least for the moment, and with only the formal disembowelling of Millwall at the Millennium Stadium to anticipate, the Keane sneer will no doubt glower back into place.

The same applies to the facial fix of his boss, Sir Alex Ferguson. The Manchester United chief tired of the Cup glory almost as soon as it had taken its place as part of the historic Treble of 1999, flying off for tinpot action in Brazil rather than defend the famous old trophy. So why was he rivalling his captain's ritual dance of victory when the referee blew time on an increasingly futile Arsenal at Villa Park on Saturday? It was because the best work of his team's season had been done.

With a record of two draws and one victory over the team that had been prematurely assigned all-time greatness, United said that their will had not been broken by Arsenal's coruscating run through the season. Inevitably, Ferguson could not help himself from the mischievous - some might say malignant - suggestion that Arsène Wenger's men will carry the defeat into Tuesday's Champions' League quarter-final second leg with Chelsea as the most disquieting of baggage. But all is surely fair in a rivalry that long ago shed the trappings, even the illusion, of mutual respect.

Though Arsenal have been the saviours of a catastrophically inferior Premiership season with the majesty of so much of their play, the neutral instinct on behalf of future competitive levels was surely to welcome the storm cloud of doubt that suddenly appeared when Paul Scholes yet again reminded us of his vast contribution to United's past success with his perfectly drilled winner.

It was a beautifully worked goal, with Gary Neville's biting pass to Ryan Giggs, who had made yards of space for himself, and the killer execution of Scholes, but it was most significant for the damage it did to Arsenal's self-belief. It is they who are supposed to be the masters of demoralisation, and that they too are capable of being surgically dismantled in the course of a few seconds was plainly a revelation of some psychological devastation.

It was maybe as much as Wenger deserved for his airily conducted debate about whether or not he might leave out the player of the season and perhaps the decade, Thierry Henry. In the end he did, and the need to bring him on, when the effect of his absence had been cripplingly apparent, was not just a tactical adjustment but a massive loss of face.

United, who had the additional satisfaction of winning without their warrior-talisman Ruud van Nistelrooy, took Henry in their increasingly confident stride when he eventually appeared after 57 minutes. By then Wes Brown's resurrection as a central defender of formidable talent and nerve, one helpfully - or not - coming before the eyes of the England coach, Sven Goran Eriksson, was just about complete.

The agony for Wenger must concern whether he merely lost the third and least prestigious element of the Treble triumph with which he hoped to beat Ferguson over the head five years after the Scot was knighted for the achievement. Instead of that, the Frenchman, after maybe the most perfuctory handshake in the history of unarmed combat, must have had at least a twinge of foreboding that an extraordinary spell had been broken.

He has been fretting for several weeks over signs of weariness in his virtuoso team; now he must worry that United have, at a vital moment, reopened old doubts about Arsenal's ability to fulfil the promise of some exquisite foreplay. That surely has always been the proper reservation over increasingly wild claims that Arsenal's recent work has made them contenders for the title of the greatest club team in the history of English football - better even than the Spurs of White, Mackay, Blanchflower and Jones, and four-times European Cup-winning Liverpool. That has always been something of a reach, and the competitive edge exerted by United at the very least must have been considerable encouragement to Claudio Ranier's Chelsea.

Arsenal brought a rare aura to Villa Park but at the end it had unquestionably been reduced. That was why Keane was so exultant, and Ferguson reproduced his choreography of triumph on the Nou Camp touchline in 1999. It wasn't, don't think it for a second, about winning the dear old Cup. It was to do with hitting the tormenting Arsenal where it hurt most. That was in minds already suspect in their ability to resist the damaging effects of hubris.