Sunderland midfielder Kieran Richardson will be out of action for up to three months with a stress fracture of the back.

Richardson, a summer signing from Manchester United, missed out on returning to Old Trafford after complaining of the injury which tests have revealed to be worse than anticipated.

Manager Roy Keane told the club's website, www.safc.com: "We'll have more news after he sees a surgeon later today. I would have thought that he'll be out for two to three months.

"It's a major disappointment. Kieran was able to do elements of training but it affected him when he twisted or hit the ball hard. In the last week or two we were hoping that it might settle down but clearly it's a lot more serious."