Sunderland boss Steve Bruce believes inconsistency is inevitable as he attempts to instil a winning mentality into his remodelled squad.

The Wearsiders would have gone fourth in the Premier League on Saturday had they not slumped to a 2-1 defeat at Birmingham with a lethargic performance which failed to reach the heights shown in the games against Manchester United and Liverpool.

Although questions have been asked about the size of his squad following some notable summer departures, Bruce feels losses such as the one at St Andrew's can be attributed to the squad not yet being tuned into his way of thinking.

Speaking ahead of Tuesday night's Carling Cup clash against Aston Villa, he said: "I have chosen to go that way with the size of the squad and you just hope you don't get any serious injuries.

"Obviously Lee Cattermole's is a serious injury but I am not going to use that as an excuse. I believe it's a mental thing.

"But we can't forget this club only just survived by the skin of its teeth last season so we can't expect it all to turn around in a few months.

"This club has only been in the Premier League for a little over two years and there are going to be ups and downs.

"You can't play well week in, week out but we look a little bit fragile away from home and we need to do something about it."

Bruce has maintained from the moment he arrived at the Stadium of Light that the Carling Cup is a tournament the club can win and he is likely to put out a strong side against Villa.

He will be without leading scorer Darren Bent though, with the former Tottenham striker sustaining a knee injury at the weekend.

Bruce remains hopeful Bent will be ready for Saturday's visit of West Ham and was relieved it was not more serious.

He said: "He has had a bad knock, it wobbled his knee a bit, gave him a fright.

"It was close to being serious but I don't think it is fortunately. It's not ligaments. He twisted his knee, rattled everything inside."

Bent will be joined on the sidelines against Villa by defenders John Mensah and Phil Bardsley but, that trio aside, Bruce will field an XI he feels is capable of bringing some cup fever to Wearside.

"If you can get on a cup run it can give the whole club, the whole area a boost," he said.

"I think the fans want to see you take it seriously and we have a chance, we are a Premier League team.

"But this competition is more difficult than the FA Cup as the big boys don't come into it until later."