England defender Micah Richards on Tuesday underwent an operation on his right knee after picking up an injury for Manchester City against Swansea last weekend, the Premier League champions said.
The northwest club said that the 24-year-old would be out for between six to eight weeks. He damaged his cartilage while changing direction in Saturday's match, which City won 1-0, and no other player was involved.
Richards has played four times this season and had only recently returned from a serious heel injury. City are already without defenders Maicon and Pablo Zabaleta, although the Argentinian could return for this weekend's match against West Ham.