Arsenal manager Arsene Wenger says Olivier Giroud made a "big mistake" after being sent-off during Arsenal's 2-1 win over QPR.

Giroud's 53rd-minute red card for headbutting Nedum Onuoha threatened to deny Wenger a 400th Premier League win as Arsenal manager, but the Gunners held their nerve to claim all three points in a tense finale.

Alexis Sanchez has now scored or assisted half of Arsenal's 32 Premier League goals this season, scoring 10 times and providing six assists.