Sunderland have been dealt a significant injury blow with Younes Kaboul ruled out for several weeks with a hamstring problem.
Summer signing Kaboul had begun to enjoy a much-improved run of form under Sam Allardyce, but the French international has now been ruled out of Sunderland's festive programme.
It leaves Allardyce with just John O'Shea and Sebastian Coates - plus veteran Wes Brown - as available central defensive options for Boxing Day's trip to Manchester City.
Allardyce has been looking at a host of central defenders in the transfer market over recent weeks and will now step up his efforts to recruit at least a fresh face at the back in the January window.
"Younes tore his hamstring in the Chelsea match and quite frankly we were a little bit surprised that he managed to carry on until the end," said Allardyce.
"He'll be out for a few weeks now."
Summer capture Adam Matthews has added to Sunderland's defensive absentees, with the Welsh international out with ankle ligament damage.
Midfielder pair Seb Larsson and Lee Cattermole are unlikely to be involved at City, although the latter has now returned to training and has an outside chance of being included in the squad.
"I'm not sure whether Lee is back yet, we'll have to wait and see," added Allardyce.
"We have to get the full consent of the player for me after he's had the back injury that has reoccurred.
"He needs to say 'yes gaffer, I'm ready to go'. I'll ask that question tomorrow."