There is a question mark hanging over Kolo Toure's fitness for the trip to Old Trafford on Sunday.
The centre back injured his hip in the 2-1 win at Hamburg last night and was forced off after 29 minutes.
"It was a kick on the hip," said Arsène Wenger afterwards. "It looks like muscle damage.
"We do not know if he can play on Sunday [against Manchester United] at the moment. It is very difficult to say."
Arsenal.com hope to have an injury update later on Thursday
Copyright 2016 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source