Joshua Kimmich is out for the rest of the Bundesliga season after suffering a serious leg injury during training on Tuesday.
The Bayern Munich defender, who has been in excellent form this season, was forced off in the second half of the team's match against Wolfsburg and underwent surgery to repair a torn cruciate ligament in his right knee.
Kimmich, who joined Manchester City from Bayern in January 2019, has made 48 appearances for the club so far and has scored four goals.
He has also been a key player for Germany at international level, appearing in all three of their World Cup qualifying matches this year.
His absence will be a major blow for Bayern, who are currently top of the Bundesliga table and looking to defend their title.
However, they have plenty of depth in their defence, with Lucas Hernandez and David Alaba also capable of filling in for Kimmich if needed.
Bayern manager Julian Nagelsmann said: "We're very disappointed that Joshua won't be able to play for us for the next few months. He's been one of our best players this season and we'll miss him.
"But we have other defenders who can step up and help us, especially when it comes to defending set-pieces."
Manchester City manager Pep Guardiola has also expressed disappointment at the news, saying: "It's a huge loss for Joshua and for the team.
"We wish him a speedy recovery and hope he can be back in time for the new season."