Sunderland boss David Moyes says centre-back Lamine Kone "doesn't want" a new contract, prompting fresh speculation that he will leave the club in this transfer window.
Everton have a bid on the table for the 27-year-old although Sunderland have expressed their determination to keep him on Wearside by offering him a new deal worth a reported £50,000 a week.
Kone, who played in the season-opening 2-1 defeat at Manchester City last weekend, has refused to consider the offer, however, and has also ruled himself out of Sunday's Wear-Tees clash with Middlesbrough due to a back problem.
"We want to keep him. We made him an offer of a new contract which as of this moment in time he has refused. He came in this morning with a bad back so he won't be available for the Middlesbrough game," said Moyes.
"He's a very good player, we don't want to lose him. I've told him that from the start. I don't know if he's actually refused it but he said he didn't really want the offer.
"He's a good boy, I've enjoyed working with him. We hope that he sees we want him to be here, although obviously we've got an offer from Everton."
The news comes as a blow for Sunderland, who announced on Thursday that they had accepted a bid from Watford for Kone's central defensive partner Younes Kaboul, who has told the club he wishes to leave for personal reasons.
"We got an enquiry from Watford and Younes said he would like to go back, his family home is there, so reluctantly we agreed to it," Moyes said. "You're always disappointed but there are always new things on the horizon."
Sunderland have since been linked with a possible bid for former Manchester City and Everton defender Joleon Lescott, but Moyes has denied interest in the Aston Villa man.
"Joleon was great for me at Everton, but we've bought a left-footed centre-back so we were never really in for him," he said.
Papy Djilobodji is set to make his debut for Moyes' side when they host Aitor Karanka's Middlesbrough, with fellow new signing Paddy McNair or veteran John O'Shea expected to line up alongside him.
Sunderland are also facing real problems in midfield, however, with Moyes confirming that Lee Cattermole will be out for up to six weeks, while Jan Kirchhoff is sidelined with a hamstring problem and Fabio Borini is a doubt with a toe injury.
New signing Steven Pienaar, who joined on a year-long deal on Friday, could be thrown straight into the side for a derby game that Moyes hopes will get the crowd firmly behind the team.
"The only thing I'm interested in is winning," the ex-Manchester United boss added. "We don't want to be playing catch up so the earlier we get the wins the better. Hopefully that starts on Sunday.
"It is a big derby game and a game you have to treat like all the others. But we'll have great support and it gives players every opportunity.
"Middlesbrough getting promoted was a great thing. They've strengthened the squad, but we know it will be a long haul."
