Pep Guardiola has confirmed that Benjamin Mendy will miss 10-12 weeks with a knee injury, after undergoing surgery during the international break.
The left back played 90 minutes in City's 3-1 win over city rivals Manchester United, but reportedly felt a twinge in his knee during the game.
He was advised to pull out of the France squad in order to receive treatment, and Guardiola confirmed in a press conference, as per City's Twitter account, that he will miss around three months of action.
He also confirmed that Bernardo Silva will sit out this weekend's clash with West Ham, but did not confirm whether or not the Portuguese international will be available for City's Champions League clash against Lyon in midweek.
Silva has been in sensational form for Guardiola' side this season, seizing his opportunity to impress after star midfielder Kevin de Bruyne was sidelined with a knee ligament injury earlier in the season.
As far as Mendy goes, it's an unfortunate blow in a fledgling City career that has threatened to be blighted by injuries in the past. He missed the vast majority of last season with a cruciate ligament injury, but bounced back to become an important player in City's defence of the Premier League crown so far, save for a three game absence with a foot injury in September.
In Mendy's absence, it's likely either Fabien Delph or Aymeric Laporte will fill in at left back for the time being, with Olaksandr Zinchenko another option.