Chelsea have escaped Wenger, and United have reminded him that retaining a Premiership title is still the preserve of only one club in this country. From 24 October last year, when their 49-game run came to an end, Arsenal's fall from a position of pre-eminence has become a self-fulfilling prophecy: a tiny squad, an exhausting reliance on the stellar performers and the absence of a goalkeeper upon whom the manager could rely. Once the fissures appeared at Old Trafford, they opened at a rate that no one outside Highbury dared believe possible.
When, on Tuesday night, United's victory turned Arsenal's October 11- point lead over them to a deficit of two it was first Wenger's defence that buckled and then his attack that failed to come to the rescue. Only the most unforgiving would describe a team who are third in the Premiership, in the fifth round of the FA Cup and the knock-out stages of the Champions' League as victims of a collapse. But on the night Wenger conceded the title, Highbury did witness a temporary surrender.
So what has happened to the champions who had opened their campaign with a series of dazzling performances and were drawing comparisons with the greatest club sides ever assembled?
"We gave goals away," Wenger said. "You could see that the same defence that has done so well did not have the confidence they used to have." Not quite the same defence when you consider that Pascal Cygan was again called upon to deputise for Kolo Toure. How costly that elbow he swung at Alan Shearer on 23 January now seems. Any interruption in the Sol Campbell- Toure axis appears to invite disaster and, with the latter still suspended, the England defender is also an injury doubt for the weekend.
Wenger also mentioned on Tuesday how he had observed a "casual" approach in his defence at the start of the season, which went unnoticed amid the triumph of the unbeaten run. Certainly, the three goals conceded at home to Middlesbrough on 22 August were a portent of the difficulties to come. Arsenal have now conceded 29 League goals this season, which is already three more than in the last campaign.
The PFA Footballer of the Year has not scored in the Premiership since Boxing Day, but when you check his service record it becomes clear why. His 25 Premiership appearances are more than any United player this season and only one fewer than Alan Smith and Wayne Rooney's records combined. There is no alternative at Highbury to their No 14 and it has started to show. Against two United full-backs for whom pace is not a luxury, the Arsenal striker failed to use his own searing acceleration.
Strange that a player who normally uses his reputation to talk the referee through the game, should choose to try talking tough in the tunnel. It can hardly be ignored that for much of the summer, Vieira must have felt that his future lay at Real Madrid. He has been through the same before and subsequently readjusted to life at Highbury, but this season that has looked beyond him.
There will be little comfort for Manuel Almunia in the replays of United's third goal on Tuesday night, although the Spanish goalkeeper can at least be reassured that Wenger has refused to blame him. The decision to try to tackle Ryan Giggs on the edge of the area was an error of judgement. Jens Lehmann's decline mirrored Arsenal's but they are not the first team - as the careers of Jerzy Dudek and Tim Howard show - to discover that the Premiership is unforgiving to even the very best goalkeepers.
It is the greatest testament to Wenger's talents that he built a team on a budget in the era that football was tamed by big money. Now, more than ever, he needs the resources to reinforce his squad. Three times - in Vieira, Henry and Robert Pires - he has plucked from relative obscurity the kind of player who ordinarily would be beyond Arsenal's budget. To do it again, with Chelsea following his every move, would be miraculous.
Unusually, it has been the one signing that has really cost Arsenal who remains a doubt. After a year at Arsenal, you would have expected Jose Antonio Reyes - at pounds 10.5m - to be an obvious starter in a game of Tuesday's magnitude. His treatment at Old Trafford in October seems to have slowed his progress and placed even more burden on Dennis Bergkamp.
Cristiano Ronaldo and Giggs imposed themselves down either touchline on Tuesday night without ever looking under threat from Pires and Freddie Ljungberg. When Arsenal roll forward, their two first-choice wingers are unmatched - when they are rocked back on their heels both can be found wanting. The tackle that Pires lost to Darren Fletcher for United's second goal was crucial. It made the Arsenal midfield look physically vulnerable and they struggled to recover.
It was with some justification that Wenger warned on Monday that the English impulse to lionise the team of the moment and forget all other contenders was a dubious stance to take. The title might be heading elsewhere this season, but the values and the philosophy that he has installed remain.
Arsenal's greatest asset is their manager, who has a deal that takes him to 2008, but their thin resources mean they cannot allow him to consolidate in the same way that United did after the Treble of 1999. The resolution of the Ashley Cole situation should at least put them in a position of some comfort: they might not be able to compete with Chelsea financially, but they are not yet selling them their own players.
THE DIFFERENCE OLD TRAFFORD MADE
When Arsenal travelled to Old Trafford on the 24 October, they were five points clear of Chelsea at the top of the Premiership, and 11 ahead of Manchester United. They had won eight of their first nine league games and were unbeaten in 49 Premiership games.
They are now third, two points behind United. Of the 15 games since then they have won just seven and lost three more, while United have won 11 and lost just once.
PREMIERSHIP TOP THREE
24 October 2004
P W D L F A Pts
1 Arsenal 9 8 1 0 29 8 25
2 Chelsea 9 6 2 1 8 2 20
6 Man Utd 9 3 5 1 9 7 14
3 February 2005
P W D L F A Pts
1 Chelsea 24 19 4 1 48 8 61
2 Man Utd 25 15 8 2 41 16 53
3 Arsenal 25 15 6 4 55 29 51
does not include last night's matches