CROCKED Sunderland winger Thomas Butler is sweating on whether or not he will need an operation on his damaged ankle.

The Republic of Ireland Under-21 midfielder has been sidelined since picking up an injury in Sunderland's 1-0 victory at Sheffield United early last month.

And manager Mick McCarthy admits the time is close to deciding whether or not he needs to go under the surgeon's knife.

Butler went over on his ankle, badly straining muscle fibres, but the club had been hoping that the injury would heal naturally with careful rehabilitation.

But so far the injury has failed to mend and, after several setbacks, a decision is expected to be made next week on whether surgery will ultimately be necessary.

The Sunderland boss said: "We're just going to have to wait and see how Tommy gets on.

"If he breaks down again, then there's likely to be no other option and it will be the only way forward."

Butler's injury is desperately disappointing for the 22-year-old, who worked hard to do a job for Sunderland on the left flank in the wake of Kevin Kilbane's departure to Everton in August.

The Irishman has been with Sunderland since he was a youngster, making his name initially as a gifted central midfielder.

But he has played on the right wing for his country at Under-21 level while, for the first team at club level, he has made most of his appearances on the left.

He told the Echo earlier this season that he didn't really care where he played across the middle just so long as he was getting games regularly and was given a position on the field he could specialise in.

He had hoped to make a success of the left-wing role, but injury has curtailed that plan and the arrival of Stewart Downing from Middlesbrough looks likely to limit his chances further, even if an operation proves unnecessary.

McCarthy, though, has been pleased with the efforts of those who have filled in on the left since Kilbane moved to Everton earlier this season, even though he now hopes Downing will go on to establish himself as the club's first-choice left winger over the next few weeks.

He said: "It's good to have Stewart in and I'm hoping he will give us balance, being a natural left-footed player.

"But I'm not decrying the efforts of any of the players who have operated there over the last couple of months.

"They've given it their all and I couldn't have asked any more of them.

"They've also helped us towards some good results over the past few months which have helped put us up there among the play-off places."