Arsenal boss Arsene Wenger felt they deserved something from their 1-0 defeat at Manchester City.
David Silva slid in his sixth goal of the season after Mario Balotelli had another shot saved and Pablo Zabaleta then hit the post.
But Arsenal also tested Joe Hart and had a penalty appeal for handball against Micah Richards turned down.
Arsenal manager Arsene Wenger said: "I haven't seen it, but (Robin) van Persie is adamant - 100% penalty.
"We were unlucky as we had to reshuffle at the back in a position where we are already short.
"I did feel at half-time we could win the game if we stayed stable at the back, and we lacked a bit of accuracy in our final ball and in the final third as well.
"We had a few opportunities where we didn't pass the ball well.
"Overall we had a positive performance, great spirit, quality but we lacked a little bit and that's vital in the big games.""It was a game where it could have gone both ways. It was very intense with both teams going for it. I felt we were a bit unlucky and their keeper had a good game.