Manchester City defender Micah Richards out for as long as four months

Micah Richards is taken off in the Premier League game against Swansea (GETTY IMAGES)

Manchester City defender Micah Richards is expected to be out for around 16 weeks having undergone knee surgery.

The 24-year-old had an operation late last night after an assessment revealed cartilage damage.

The decision to operate came after the defender was stretchered off during Saturday's Premier League game against Swansea with a little less than a quarter of an hour remaining in the match.

It is a blow to Richards who missed the start of the season having picked up an ankle injury while representing Team GB at the London Olympics.

He returned in City's 3-0 win over Sunderland - one of only two clean sheets the Premier League champions have kept in 14 matches this season. Richards made only a further three appearances before this latest setback.

Richards left the pitch at the Etihad with the aid of an oxygen mask in an incident that led to 12 minutes of injury time in the match which finished 1-0 to the home side.

"The positive thing is that the injury has been repaired so the knee will be as good as new," he said.

"I have a brace on it and I am using crutches. I can't do anything at all for the next four to six weeks and I am probably looking at 12-16 weeks before I am back in action."

The injury provides yet more defensive problems for the Roberto Mancini who has seen his side, built on defensive stability, conceding goals for fun so far this term. City's other options on the right side of defence are Pablo Zabaleta and Maicon who are already sidelined with hamstring and foot problems respectively.