ROY Keane last night insisted Graham Kavanagh's knee operation was a case of "short-term pain for long-term gain", but the Sunderland boss admitted he was growing increasingly concerned at his side's lengthening injury list.

Kavanagh underwent surgery yesterday to repair some long-term cartilage damage that was proving increasingly problematic.

The 32-year-old midfielder, who has impressed since making a deadline-day move, is expected to be out of action for more than a month and could miss up to seven league games as well as the Republic of Ireland's double header with Cyprus and Czech Republic.

Kavanagh could have played through the pain barrier for another couple of weeks, but rather than running the risk of inflicting more serious damage Keane has opted to nip the problem in the bud.

"Graham's fine, but he's understandably disappointed," said the Black Cats boss, who will also be without the services of suspended midfielder Ross Wallace when Sheffield Wednesday visit the Stadium of Light tomorrow. "He's had a problem since pre-season, but it's got worse in the last couple of games.

"He struggled against Ipswich and it was clear that something wasn't right. He was in a lot of pain afterwards, but because of the type of person he is, he didn't want to say too much.

"I had a chat with him and said, 'If there's something not right, get in and have it done'. I'm not one who's quick to throw players in for operations but, if a player's not right, something needs to be done.

"He'll miss games for us and he'll miss the games for Ireland, so that's a blow to him. But I'd rather have him fit and strong in four weeks' time than have someone who's going to struggle for the next few months."

Kavanagh's setback is merely the latest injury blow to have blighted Keane's plans.

Stephen Elliott, David Connolly, Steve Caldwell and Stephen Wright are all out of tomorrow's game, while Jon Stead, Daryl Murphy and Neill Collins face late fitness tests before their possible participation is confirmed.

Keane's deadline-day dealings mean that Sunderland have a deep enough squad to cope with such a plethora of absentees.

But with the injuries continuing to mount, the Black Cats boss has admitted he may have to reassess his squad's training regime in an attempt to prevent further problems from occurring.

"They're dropping like flies at the minute," said Keane. "So we might have to have a look at some different aspects of the training. I haven't told anyone to tone anything down yet, but it's something I might have to do.

"It's all about getting a balance. I'd rather they were going in for tackles than not touching each other, but we might have to look at how we're setting up the games. Maybe it's too tight an area and the players are getting in tackles too close.

"If the ball's there to be won, I want them to go in and win it, but we've picked up a couple of knocks this week from late tackles. Maybe they're trying too hard to impress, although I suppose I see that as a positive."

There was at least some good news for Keane yesterday after he came to an agreement with Dwight Yorke regarding the striker's plans for the international break.

Yorke will travel to his native Trinidad & Tobago after tomorrow's game with Sheffield Wednesday and represent his country in a friendly against Nicaragua on October 7.

However, he will return to England ahead of T&T's second friendly with Panama, ensuring he will be sufficiently rested by the time Sunderland line up against Preston on October 14.

"He won't be going to the next World Cup and he's got a commitment here for two seasons, but Trinidad see Dwight as an ambassador and their main man," explained Keane.

"I'd never begrudge a player a chance to play for his country so, after this week's conversation, he's going to play in the first game and miss the second one.

"That'll mean he's back here on the Sunday or Monday and that's the way we're going to play it.

"He's not getting any younger and the games are just friendlies, so it's about getting the balance right and being fair to everyone."