Sunderland will be without Wes Brown for eight weeks but Lee Cattermole is hoping to be back in training next week.
Brown picked up a knee ligament injury in the 1-1 draw against Middlesbrough at the weekend and it was initially feared he would need an operation that would put him out for the season.
Martin O'Neill has confirmed that is not the case but says the player is still looking at two months out.
"We don't think he needs the operation, but he will be two weeks in a brace, two weeks elsewhere and you are looking at probably about eight weeks before he is back," he said.
"But at one stage, it looked like a season-ending injury."
However, there is better news regarding midfielder Cattermole, who suffered a hamstring strain in training.
O'Neill added: "Lee is feeling a lot better and he is hoping to start running at the back end of next week."