Arsenal right back Mathieu Debuchy was stretchered off during the 2-2 draw with Manchester City leaving Arsene Wenger with an early-season defensive crisis.
Debuchy sprained his ankle late in the game at Emirates Stadium and was replaced by England youngster Calum Chambers, who will deputise at right back for the Frenchman.
Although a fracture has been ruled out, Wenger fears that Debuchy has suffered significant ligament damage which could rule him out until Christmas.
Speaking in his post-match press conference, Wenger said: “Debuchy has a bad ankle sprain. I don’t know how long he will be out for, but it does not look too good. They [the medical staff] need more time to assess how long he will be out.”
It leaves Arsenal desperately short of defensive options so early in the season and could mean academy talents Hector Bellerin and Isaac Hayden being fast-tracked into first team action ahead of schedule.
Arsenal travel to Borussia Dortmund to kick off their Champions League campaign before taking on Aston Villa on Saturday and Wenger will be hoping to avoid any more defensive injuries.