Sunderland boss Roy Keane admits he may have asked too much of some of his players during a difficult first season back in the Premier League.The Black Cats head into Saturday's crucial derby clash with Middlesbrough at the Stadium of Light still smarting from their 2-0 defeat by arch-rivals Newcastle last weekend and with injuries once again hampering their efforts to drag themselves to safety.

Keane was dealt a huge blow ahead of the game at St James' Park when in-form defenders Jonny Evans and Phil Bardsley were forced to withdraw with hamstring and knee problems respectively.

Fitness concerns have become depressingly familiar for the manager, who has missed the services of the likes of skipper Dean Whitehead and wingers Carlos Edwards and Kieran Richardson for extended periods this season.

He has been forced repeatedly to reshuffle a small pack throughout the campaign, and he believes the physical demands on some of his troops may be starting to tell.

Keane said: "The season is maybe catching up with some of the players.

"Because of the size of the squad and the injuries, particularly at the start of the season, a lot of players have played a lot of games.

"We are putting a lot of demands on a lot of young players, and sometimes the body just says, 'I have had enough, I need a rest'.

"It's not great timing for us, but that's what you are up against with the bigger teams with the big squads.

"You understand why those clubs have 25, 26 international players because you are going to have injuries, and they can deal with it better than clubs like ourselves.

"That's what we are trying to aim for."

Keane refused to blame the loss of Evans and Bardsley for his side's tame defeat at Newcastle, and pointed instead to the defending that allowed Michael Owen to claim a match-winning double.

He admitted after the game on Tyneside the pair will be 50-50 at best to return against Boro, and rumours on Wearside have suggested both men could struggle to play again over the closing weeks of the campaign.

Bolton's win on Teesside last weekend was the last thing either Sunderland or Gareth Southgate's men needed, and although both sides remain five points clear of Birmingham in the final relegation place, a defeat for either on Saturday could make for an uncomfortable final fortnight.

Keane insisted even after seeing his team pull 10 points clear of the drop zone with a 3-1 win at Fulham on April 5 they were not safe, and his caution has proved well-founded.

However, he is equally well aware one win from their remaining three games should be more than enough, and then he can start to plan for the future.

The Irishman was adamant as he prepared for life in the top flight mere survival was short of his ambitions, but that and the chance to consolidate next time around would represent a satisfactory outcome.

But he knows the hard work has only just started.

He said: "There is plenty (to do). If I have said it once, I have said it a million times, we just believe there is a great potential in the football club.

"We are trying to build a football club and to maintain that and to try to keep lifting the standards, we have to stay in the Premier League, get stronger, bring in better players and keep pushing each other.

"I have not really scratched the surface.

"We are delighted with the progress the club is making and if we can stay in the Premier League this year, then we will be fairly pleased.

"But I keep saying, there is so much hard work ahead."

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