Arsenal defender Sol Campbell will be sidelined for two weeks after sustaining an ankle injury in the 4-2 defeat by bitter rivals Manchester United on Tuesday.
The England centre back will miss games against Aston Villa and Crystal Palace as well as the international friendly against the Netherlands at Villa Park on February 9.
Campbell, who gave away possession to give United the chance to score their opening goal, limped off in the 79th minute with a twisted ankle.
"Sol's injury leaves us short in defence," Arsenal manager Arsene Wenger said on Thursday. "I don't know exactly what I will do yet but I have a bit more time to think about it."
With Kolo Toure serving the last of a three-game ban and Philippe Senderos injured, Justin Hoyte could play in central defence at Villa alongside Pascal Cygan.