Manchester City boss Sven-Goran Eriksson expects to be without star defender Micah Richards for up to six weeks following his knee surgery.

Richards underwent surgery on a knee cartilage problem on Wednesday after suffering a recurrence of the injury.

"That's really bad news of course," Eriksson told Sky Sports News. "He was operated on yesterday in London and I spoke to the medical people before and after the operation and they said before it would be six weeks and they confirmed after the operation he will be out around six weeks. "Bad news of course but unfortunately it happens."