Arsenal boss Arsene Wenger was disappointed with Olivier Giroud's behaviour after his dismissal in victory over QPR.

Giroud reacted angrily to a push from Nedum Onuoha and headbutted the QPR defender, with Wenger conceding the clash merited a straight red card.

Alexis Sanchez and Tomas Rosicky guided Arsenal to victory, despite Charlie Austin firing a late penalty for QPR to set up a nervy finale.

"Yes, of course," said Wenger when asked if he would have stern words with Giroud behind the scenes.

"He knows that he has made a big mistake today. It was deserved, he didn't control himself and that of course, is a straight red.

"Of course (it was costly), it changed the game's dynamic completely.

"We were completely in control of the game, not in trouble, and suddenly we were down to 10 men and only one-nil up.

"We threw our bodies in after that.

"We knew we had to do that, and what I feel is that in the last four, five weeks we have defended with more resilience, even if we conceded from a set-piece to draw against Liverpool.

"Overall I think defensively we are better."