That was how the match ended, but what about its start? From early on, there did seem a sense of arrogance about Arsenal; that they felt they only had to turn up to win against a remarkably under-strength United forced to field three academy products in the starting line-up because of so many injuries. It was instead the Old Trafford kids who were impressively assertive.

Varela, Lingard, Rashford and the much-improved Memphis Depay were the players injecting all the life into this occasion. That in itself is an amazing thing to say, considering one of the teams should have been energised by the prospect of getting a big win here to potentially go on and win the title. Instead, Arsenal were so flat, and were levelled by Rashford's two storming goals in a stunning three minutes. The fact that Varela and Lingard did so well for both only added to the sense of life.

This defeat obviously doesn't kill Arsenal's title challenge, but it does create huge doubts -- perhaps most importantly -- in the team themselves. There were two particularly galling aspects to this defeat for Wenger, beyond the fact that they wasted such an opportunity. They also wasted all the momentum from the last league game, that sensational win over Leicester City.

Again, just as you wouldn't have guessed this woefully flat Arsenal side were in a title race, you wouldn't have guessed they were coming off the back of what should have been a momentum-driving last-minute winner against the league leaders. It also means the league table has reverted to what it was before that match versus the Foxes two weeks prior: Arsenal are again five points behind the Leicester.

The fact that that situation changed back so quickly did mean that Wenger was right on one thing, even if he got so much else wrong on the day: When was asked what effect this would have on the title race, the Arsenal boss replied, "Nobody knows."

It is that kind of season, to be fair, that more major errors are being committed by the contenders than most normal title races would allow. Things can swing again very quickly, and Wenger stressed the need to get a win against Swansea City on Wednesday. "We have to show we can fight and bounce back on Wednesday night and not feel sorry for ourselves."

The wonder, however, is how Wenger really feels about this performance and what it means for his team. The whole game just reflected so badly on them, from their response to adversity, to the errors made in defence, to the dispiriting limpness up front.

In a tetchy news conference afterwards, Wenger tried to rationalise it all and not show any anger. He even attempted to put a different spin on the context of the game, saying that United "still had a few millions on the pitch."

But one could sense something different. The Arsenal manager is usually polite in his dealings with the media, unless he is seething about something. That is when he tends to channel his anger by turning any piercing questions back on journalists. He did exactly that here, when asked whether he would have wanted more from Arsenal.

"It is very difficult for me to go into an individual assessment," he said. "I leave that you. You are big and strong and intelligent enough."

Arsenal's attack no longer looked like it had big players, or particularly strong-minded ones. Mesut Ozil, Alexis Sanchez and Aaron Ramsey did so little. They were gifted two goals by the United defence: one for Danny Welbeck just before half-time, one for Ozil just after Ander Herrera's deflected effort to make it 3-1. Yet they couldn't build on either.

Wenger did at least show some grace in defeat, praising Rashford. "The timing and intelligence of his movement was great," the Arsenal boss said. "He could be a very positive surprise for Man United."