Manchester City defender Alex Greenwood has undergone knee surgery on a medial collateral ligament (MCL) injury.
The captain was stretchered off in the first half of Man City's Champions League win over St Polten earlier this month.
Manager Gareth Taylor had initially said the "injury was not as bad as first feared", but a statement from the club on Thursday revealed that Greenwood required "a repair of her MCL".
Image: Greenwood suffered the injury while competing in the Champions league earlier this month
Depending on the severity of the tear, MCL recovery can take anywhere between three and 12 months, with no timeframe given for the defender's return to action.
Forwards Vivianne Miedema and Lauren Hemp are also sidelined with long-term knee injuries, while Khadija Shaw will not return until January.
[Man City lost 3-0 to Barcelona](https://www.skysports.com/football/barcelona-women-vs-manchester-city-women/report/522653) in their final game before the winter break, conceding top spot in their Champions League group, but had already sealed qualification to the knockout phase.