Sunderland boss Ricky Sbragia hopes to sign an experienced defender by the time Fulham head for Wearside next Tuesday evening.
The Scot has been trying to recruit a man with Premier League experience to add strength in depth to his resources at the back, and his need increased at the weekend when he lost Nyron Nosworthy for up to six weeks with a hamstring tear.
Sbragia told the club's official website: ''A defender has always been the number one priority, but we might have to do it a bit quicker now.
''I have spent a lot of time working on possible replacements in the last couple of days. Hopefully we will get one before the Fulham game.''
Sbragia recalled Republic of Ireland international Paul McShane from his loan spell at Hull City last week after going into the derby clash with Middlesbrough on January 10 with only four fit defenders.
He lost Danny Collins with concussion, as well as Nosworthy, during the 2-1 home defeat by Aston Villa on Saturday, although the former is expected to return for Saturday's FA Cup fourth round tie against Blackburn Rovers.
However, full-back Phil Bardsley, like midfielder Dean Whitehead, is currently on four bookings and knows another will bring him a one-match ban.
That, coupled with Nosworthy's injury, has increased Sbragia's desire to add to his options before Fulham arrive at the Stadium of Light on Tuesday.
In the longer-term, George McCartney is back in training after foot surgery.