Calum Chambers has undergone surgery on the knee injury that Arsenal fear has ended his season and has forced head coach Mikel Arteta to change his plans for the January transfer window.

Central defender Chambers suffered anterior cruciate ligament damage in the defeat to Chelsea, which leaves Arteta short of options at the back.

Arteta had made signing a new midfielder, with Adrien Rabiot among his targets, his number one priority for January, but hinted he will now have to sign a new defender to cover for the loss of Chambers.

Red Bull Leipzig’s Dayot Upamecano, Bournemouth’s Nathan Ake, who is also on Chelsea’s radar and can play a variety of positions, and Daniele Rugani of Juventus are all thought to be in Arsenal’s thoughts.

Asked what Arsenal fans can expect from this month’s transfer window, Arteta said: “That we will try to be in the market to see options that can strengthen the team, that’s for sure and that’s our obligation. We are going to be working on that.