STEVE Bruce last night admitted Sunderland have become over-reliant on their leading goalscorer Darren Bent.

The Black Cats drew 0-0 at Blackburn despite playing against ten men for the whole of the second half, and while they are now unbeaten in their last five matches, their failure to win any of them is a cause for concern.

Bent missed Sunderland's best two chances at Ewood Park, aiming a first-half shot straight at Paul Robinson and heading wide after the interval following a right-wing cross from Ahmed Elmohamady.

The England international started as a lone striker despite the presence of record signing Asamoah Gyan, who is still to make a single Premier League start following August's club-record move from Rennes.

Bruce has so far resisted the temptation to switch to a 4-4-2 formation that would accommodate both strikers, but the Sunderland boss admits his side struggle to carry much of a threat when Bent is failing to fire.

“Our Achilles heel is that we can't keep relying on Darren to score us a goal,” said Bruce. “He might have taken two or three chances on another night, but we've got to contribute goals from somewhere else.

“We've had enough attempts on goal and really we should have taken some. We've created enough chances but we're not scoring enough goals.

“Darren hasn't trained all week, he's been on the treatment table. He still got into the right positions though. But we can't keep relying on him to be the one that puts the ball away.”

Bent has scored five of Sunderland's seven Premier League goals this season, with the others coming courtesy of Gyan and an own goal from Stephen Carr on the opening weekend.

The entire Black Cats midfield have failed to find the target, and improving that statistic will be a key focus in forthcoming weeks.

On the plus side, however, the Wearsiders are defending superbly, and last night's clean sheet owed much to a pair of stand-out displays from centre-halves Titus Bramble and Michael Turner, allied to another strong showing from goalkeeper Simon Mignolet.

“There were some very good signs,” said Bruce. “My two centre-halves and goalkeeper were terrific, they throw balls in your box and when the ball's dead you've got to defend it. We are young and naïve.

“I'm very pleased with what we've got and what we've done. We've got the makings of a very good young side.”

Sunderland were handed a major disadvantage on the stroke of half-time last night when Chris Samba was dismissed for a professional foul on Danny Welbeck.

Sam Allardyce has been a regular criticiser of referees in the past, but the Blackburn boss agreed with Lee Probert's decision to brandish a straight red card.

“I've got no complaints,” said Allardyce. “Chris got himself in a muddle, he messed up his first touch and pulled Welbeck back. He got the red card he deserved.

“He’s very down about the situation, he feels as though he’s let the lads down, but these things happen over the course of a season. It’s our first sending off this year and it’s not for a dirty or a nasty challenge.”