After scans on his right leg after Xhaka suffered the issue against Tottenham Hotspur, the Swiss was found to have suffered a “significant” injury to his medial ligament.
While it does not require surgery, Mikel Arteta may now potentially be without the former club captain until beyond Christmas.
“Granit’s recovery and rehabilitation programme will start immediately and we are aiming for him to be back in action in approximately three months,” said a statement from the club confirming the injury.
“Everyone at the club will now be supporting and working hard with Granit to get him back on the pitch as soon as possible.”
Xhaka started the North London derby alongside Thomas Partey in the Arsenal midfield, but had reportedly been seen in a knee brace after the fixture at the Emirates Stadium.
Fellow midfielder Mohamed Elneny is only recently returned to fitness after his own injury issues, though Albert Sambi Lokonga and Ainsley Maitland-Niles will also vie for spots in Arteta’s first-choice side with Xhaka ruled out.