Manchester City defender Aymeric Laporte underwent surgery in Barcelona on Wednesday after getting injured in Saturday's win over Brighton.
The centre-back, who had to withdraw from the France squad, will be out for several months, although the injury is not as bad as City feared.
The Premier League champions thought it could have been ligament damage, but in the end, it was just meniscus.
"Aymeric Laporte has undergone surgery on his knee after damaging his cartilage and lateral meniscus during Saturday’s win over Brighton," the club said.
"The surgery, carried out by Dr Ramon Cugat in Barcelona, was successful and a more detailed prognosis will be provided in due course."
Pep Guardiola will have to improvise in the middle of his defence now. Along with Nicolas Otamendi and John Stones, he may opt to drop midfielder Fernandinho back.