Sunderland continue to be linked with a move for Steven Caulker, amidst uncertainty over the Black Cats' pursuit of fellow centre-half Lamine Kone.
Sam Allardyce admitted after Sunderland's crucial win over Aston Villa that the Black Cats were "not yet" on the verge of making a breakthrough in the transfer market, with the January window now open.
Sunderland agreed a fee with French side Lorient for centre-half Kone last week and it was anticipated on the other side of the Channel that the move would be signed and sealed by the weekend.
There have been rumours over a hitch in the deal, although Sunderland sources insist the club's pursuit of the Ivory Coast international is still alive.
But despite veteran Wes Brown performing well in the last two games, Allardyce is in desperate need of a new centre-half this month, particularly with Younes Kaboul ruled out until the end of February.
Sunderland have watched several potential options over recent weeks, including Bayern Munich's Jan Kirchhoff.
And they have also made an enquiry for England international Steven Caulker, who has made just three Premier League appearances during a loan spell at Southampton this season.
Southampton would have to terminate Caulker's deal to allow him to return to parent club QPR, if Sunderland were to sign the 24-year-old, but the Black Cats do still have one domestic loan available.
Meanwhile, Sunderland midfielder Liam Bridcutt is on the verge of extending his loan deal at Championship Leeds United until the end of the season.
Bridcutt has impressed at Elland Road since heading out on loan in November and despite interest from the 26-year-old's former club Brighton, Leeds boss Steve Evans expects fresh terms to be rubber-stamped.
Evans said: "Nothing has been signed, but we have an agreement with Sunderland that they will be honouring.
"Liam Bridcutt’s told me, 100%, that he wants to be at Leeds United until the end of the season and review his position with Sunderland then.
"My understanding is that it will be completed on Monday."