After a game in which Arsenal surrendered a 1-0 lead to lose to Manchester United and Arsene Wenger was sent to the stands in the dying seconds, the Gunners manager admitted that the result at Old Trafford was 'difficult to accept'.
Andrei Arshavin put Arsenal in front with a thunderous strike in the first half but Wayne Rooney converted a penalty after the break and Abou Diaby headed into his own net to end the visiting side's 100% start to the season.
The match concluded with more than a hint of farce as Wenger was sent to the stands for kicking a water bottle after Robin van Persie rightly had a goal disallowed for offside, and responded by standing above the Arsenal bench before being ordered away.
The Frenchman, who staunchly defended Eduardo after the striker was charged by Uefa with deceiving a referee on Friday, also backed his side again after Emmanuel Eboue was shown a yellow card for simulation.
"We go home with no points and that is very frustrating," Wenger said. "When you play like that to go home with no points is very difficult to accept.
"You know what you get at Old Trafford when you come - every time - but I don't want to go into the performance of the ref. If you have any questions you shouldn't ask them to me. I believe you should look at the game and who played with real spirit on the pitch today. I felt we played with the right spirit.
"It's difficult to judge every time someone goes down. Today I've seen a player make 20 fouls and there was no yellow card. Nobody sees it."
Asked to elaborate on the identity of the player, Wenger added: "If you've seen the game you don't need me (to tell you). How this player got away without a yellow card is quite amazing. But I'm very positive because we showed great quality. Our performance is very encouraging for the future and there are more positives than negatives from today's game."
Asked why he was sent to the stands, the Frenchman said: "Because I kicked a bottle when the goal was cancelled from an offside position. I didn't know we were not allowed not to do that."
Manchester United manager Sir Alex Ferguson reserved special praise for Scottish midfielder Darren Fletcher following the victory which took his side into third place, three points behind Tottenham and Chelsea.
Ferguson said: "Darren was outstanding, it was a marvellous performance and he's a big game player. Wayne had a fantastic second half but I'd give man of the match to Darren, although we had a lot of good players in the second half.
"One down at half-time it's always an uphill task against a team of Arsenal's capabilities. We had to dig deep and I think in fairness we really did perform well in the second half. Last season we lost four points to Arsenal...six to Liverpool. You have to try to correct these things as best you can."
The Scot had few complaints about the performance of referee Mike Dean, who turned down Arsenal claims for a penalty when Andrei Arshavin appeared to be brought down by Fletcher in the first half - but awarded one after the break when Almunia caught Rooney.
Ferguson continued: "Clearly Darren got the ball in the first half and the referee was 10 yards away. He got the ball and the ref got it right."