Sunderland defender Carlos Cuellar has been hit with a hamstring injury.
The former Aston Villa and Rangers player is expected to miss the clash with West Ham on Saturday, and could also be absent for the forthcoming fixtures against MK Dons and Wigan.
Speaking on Thursday, manager Martin O'Neill said: "Carlos Cuellar has had a hamstring problem so he will be very, very doubtful, not just for this game, but perhaps for the next couple of matches
"So from that viewpoint it is a bit disconcerting, but these things happen and you just have to get on with it."