Republic of Ireland international Andy Reid faces another month on the sidelines with a new hamstring problem.
The 27-year-old former Nottingham Forest and Tottenham Hotspur star, who recently returned to action after spending a month out of action with a similar problem, picked up the latest injury against Portsmouth a week ago.
Club physician, Dr Glen Rae, said: "Unfortunately Andy's suffered a new hamstring injury. He's working with the medical team but is likely to be missing from training for around four weeks."
Meanwhile, Black Cats boss Steve Bruce cannot believe his side have failed to win any of their last 13 matches.
He told the club's official website: "If someone had told me we wouldn't win a game for three months I'd have found it quite staggering.
"But we have to get on with it. Since the Arsenal game we've lost big players, but I wouldn't have thought it possible to be on the run we're on.
"We'll get on with it and turn it around as quickly as possible. We've been close, mighty close. Portsmouth, Everton, I can reel them off but we'll stick with our beliefs and I know things will change."