Sunderland defender Phil Bardsley has been ruled out for the rest of the season because he must undergo knee surgery.

Bardsley, 22, a January signing from Manchester United, will have surgery to repair a torn cartilage next week.

He will not figure again before the end of the current campaign - starting with Saturday's vital Premier League clash against Middlesbrough - but will be fit for the start of next season.

"Bardo is having an operation next week and he won't play again this season," Black Cats boss Roy Keane confirmed.

"It's not a major operation, it's a slight tear he has in his knee and he'll be OK for pre-season."

Bardsley's defensive colleague Jonny Evans, who also arrived from United and was absent from the derby clash with a hamstring injury, has a "50-50" chance of featuring against fellow north-east outfit Boro.

Dwight Yorke meanwhile is training again after a knee injury and may play a part.

"Yorkie didn't play in the reserves this week," Keane said. "We felt it would be better for him to have a few days' training with us. He will have an outside chance."

Striker Rade Prica is out with a virus while winger Ross Wallace is available again for selection.

Jonathan Symcox / Eurosport