Sunderland defender Carlos Cuellar is set to miss his club's next three matches after suffering a hamstring injury.
Cuellar was forced off with the injury at half-time during Sunderland's 1-1 draw against Liverpool at the Stadium of Light on Saturday and the Spaniard has been receiving treatment since then.
However, the former Aston Villa and Rangers centre-back is still struggling to recover and Sunderland manager Martin O'Neill confirmed he will be sidelined for Saturday's Premier League clash against West Ham and could also be absent for the forthcoming fixtures against Milton Keynes Dons in the League Cup and Wigan in the league.
"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," O'Neill said on Thursday.
"So from that viewpoint it is a bit disconcerting, but these things happen and you just have to get on with it."
O'Neill could also be without England winger Adam Johnson this weekend after the former Manchester City star, a £10 million pre-season signing, sustained a thigh injury last week.
"We were hoping that he would have made the fixture against Liverpool last weekend, but that wasn't the case," O'Neill added.
"He is progressing and it's too early to say about this weekend."