Manchester City defender Micah Richards has undergone surgery on a knee injury and is expected to be out for up to two months. The 24-year-old had an operation late on Monday night after sustaining the problem in Saturday's 1-0 Barclays Premier League win over Swansea, Press Association Sport understands. No official timescale is being put on his recovery by City but it is understood he is likely to be out for between six and eight weeks. The lay-off is yet another setback for Richards, who missed the start of the season with an ankle injury sustained playing for Great Britain during the London 2012 Olympics. He made his return earlier this month in the 3-0 win at home to Sunderland but after just three further appearances he finds himself sidelined once again. Richards collapsed in agony clutching his right knee in the closing stages of Saturday's game. After lengthy treatment, which contributed to an additional 12 minutes being added on at the end of the match, he left the field on a stretcher and wearing an oxygen mask. Further assessment revealed cartilage damage which required an operation. | 
