Arsene Wenger believed Arsenal had been naïve in conceding a late winner to Manchester City in the Carling Cup on Tuesday night.
The quarter-final at the Emirates was decided by a slick counter-attacking move by the visitors from an Arsenal corner.
Edin Dzeko first fed Adam Johnson the ball who flicked on for substitute Sergio Aguero to slot home with seven minutes remaining.
"It was a game of very few chances with two teams who did fight very much, but didn't create a lot and I feel we lost the game at the moment we shouldn't," Wenger told Sky Sports.
"I don't think that we should lose it because it was all about us (at that moment) - when do we score - and you could see that we were a bit naïve because it's a corner for us, goal for them.
"We didn't take enough time to take the corner and the player who was supposed to be at the back didn't have time to come back and then we lost the game.
"But overall, we gave a lot and there were some positive performances in our game."
Samir Nasri returned to the Emirates for the first time since his big-money summer switch to City and was booed by the home support.
Wenger added: "You want players who have played for us respected.
"It is his first time back, I think it was more 'disappointed love' than anger. I am sure they love him but because they love him, they responded like that - they wanted him here."
On a more positive note, young winger Alex Oxlade-Chamberlain put in an impressive performance and Wenger is excited by the former Southampton man's potential.
"Chamberlain had an excellent performance," he said. "There is a big talent there, it looks as well as though he is not fazed by the occasion and can take the pressure he was under tonight.
"How much he wants it can decide how far he can go, the potential is there."