Arsenal manager Arsene Wenger admitted he was frustrated after his side were beaten 1-0 by Manchester City in the Carling Cup quarter-final at the Emirates Stadium.
The hosts created several chances throughout the 90 minutes while City's only effort on target proved to be decisive, as Sergio Aguero converted with only seven minutes remaining.
He said: "It was an unfair result but I felt we were a bit naive. I felt as well we did not take our corners very well but overall what is frustrating is that we lost a game we looked the winner of."
He added: "We put a lot of effort in and are not rewarded. We lacked a little bit of experience to be decisive in the final third."
City boss Roberto Mancini was happy with the result, the club's first victory at Arsenal in 28 attempts.
"We had a chance seven minutes from the end and we scored. It was a great goal. A great counter-attack," he said.
"I don't think that Arsenal had a lot of chances, I think we played well.
"It will be better to win here in the Premier League but it is a good feeling because we are into the semi-finals of the competition.
"We have a strong squad - all of the top teams have a good squad and can change eight, nine or 10 players. It is normal for the Carling Cup to change.
"December and January will be crucial months because we play tough games and we play every three days. After January we can talk about whether we can win things or not."