The Black Cats head into Saturday's crucial derby with Middlesbrough at the Stadium of Light still smarting from their 2-0 defeat by rivals Newcastle United last weekend and with injuries once again hampering their efforts to drag themselves to safety.

Keane was dealt a huge blow ahead of the match 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 captain 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 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."