Sunderland manager Ricky Sbragia has stepped up his search for a defender in the January transfer window.
The Black Cats' urgency for a defender increased after the weekend's 2-1 defeat at home by Aston Villa with both Nyron Nosworthy and Danny Collins suffering knocks.
Nosworthy, who has played 16 times in the league this season, was substituted with a hamstring injury while Collins, with 19 league appearances, went off after a bang to the head.
The Sunderland defence were tormented by in-form Villa winger Ashley Young before the England international was sent off for a lunge on Dean Whitehead.
More defensive frailties were highlighted when Gabriel Agbonlahor raced through only to be fouled by Paul McShane after hesitancy by fellow defender Anton Ferdinand resulting in the penalty which won Villa the game.
West Ham duo James Collins and Calum Davenport have been touted as possible solutions to Sunderland's defensive problems with both costing around £3million.
"Nyron is going to be out for four to five weeks with a pulled hamstring," Sbragia told The Northern Echo.
"He might have torn it. We knew we needed a defender anyway, but we'll have to do it quicker now. It becomes a bit more urgent now.
"We knew Danny had a problem with his vision. We were going to try and get him off a little bit quicker, but he seemed to think he would be okay.
"Then he came over and said he still had problems on his right-hand side."
Sbragia highlighted that the enforced substitutions ruined his side's game plan against Martin O'Neill's high flyers.
"We had a bit of a game plan where after 70 minutes we were going to go, but that was blown out of the window by the substitutions."