Arsenal left-back Sead Kolasinac will be sidelined until January after injuring the ligaments in his right ankle during Sunday's 3-0 defeat by Manchester City.
The Bosnian, 26, came off after 40 minutes at the Emirates.
Arsenal say the defender is "aiming to return to full training in January."
Meanwhile, fellow left-back Kieran Tierney has had surgery after dislocating his shoulder in the 3-1 win at West Ham on 9 December.
The Scotland international is expected to return to training in March.