On-loan Sunderland striker Danny Welbeck has been ruled out for six to eight weeks after an exploratory knee operation.
Steve Bruce is said to be considering a permanent bid for Welbeck after raising substantial funds through the sale of Darren Bent to Aston Villa, but the Manchester United striker will now be out until March after having surgery on a niggling knee problem.
Meanwhile, Bruce has confirmed his interest in signing Paris St Germain midfielder Stephane Sessegnon.
"Stephane can play in the middle, out wide or in a front three and he is a good player," he said on the club's official website. "It is ongoing but it has been going on for a couple of weeks now. We're hopeful of getting something done."
Bruce added that he is looking at four or five strikers following Bent's departure but said: "We will be careful and splashing big money now just isn't going to happen."