Sunderland boss Steve Bruce is facing a defensive headache ahead of Saturday's Premier League clash against Manchester United.[LNB] The manager is likely to be without injured trio Anton Ferdinand, John Mensah and Kieran Richardson for the game at the Stadium of Light.[LNB]The Black Cats have picked up five of their seven points so far against sides classed as Champions League hopefuls, having beaten Manchester City and drawn against Arsenal and Liverpool.[LNB]Bruce will be aiming to continue his side's excellent run and will not rule out the possibility of one or more fringe players breaking into the squad ahead of the game.[LNB]Speaking to the club's official website, Bruce said: "It's a bit early to say; we'll have to look on Friday and see where we are.[LNB]"I would think that Mensah, Richardson and Ferdinand are all doubtful. The game may come a bit too quickly for them."[LNB]Bruce will also be missing the impressive Danny Welbeck, who is ineligible to play against his parent club.[LNB]"Danny will be a miss. He's played well and given us something we need on the left-hand side," he said.[LNB]"I've been very, very pleased with him of late."[LNB]The Black Cats boss has been pleased with the progress made by Fraizer Campbell.[LNB]The striker is facing at least six months out of action after undergoing an operation to repair the cruciate ligament damage he sustained against Manchester City last month.[LNB]Campbell is starting out on the road to recovery and Bruce said: "He's had his operation and he's over the worst.[LNB]"The op's been done and now he has to get his head around six months of rehab, which is never easy.[LNB]"Knowing the type of kid Fraizer is, he will give it his best shot."[LNB]The Sunderland boss also revealed that David Meyler, who also suffered a knee injury, could be back in training in around a month or so.