Sunderland have confirmed that they have accepted an offer from relegation rivals Crystal Palace for full-back Patrick van Aanholt.
The 26-year-old is in talks with the Selhurst Park club after handing in a transfer request at the Stadium of Light.
Palace are reported to have had a bid of £14million accepted for the left-back, who will undergo a medical on Friday.
"Sunderland AFC has given Patrick van Aanholt permission to speak to Crystal Palace, after the defender advised officials that he no longer wanted to play for the club and submitted a transfer request," a Sunderland statement confirmed.
"Chief executive, Martin Bain said: 'If a player openly states he does not want to play for our club, then it is clear that we have a decision to make. In this instance and in regard to this particular player, we have done what we feel is right for Sunderland, which will always be our priority.'
"The club has accepted a bid for the defender, who has been given permission to travel to London for talks."
Palace boss Sam Allardyce, who steered Sunderland to survival last season, later confirmed in a news conference: "He's in the process [of a medical] at the moment.
"Van Aanholt was a major saviour in our run at Sunderland last season. A major part of that success story."
The news will come as a blow to David Moyes' side, who are three points adrift of safety at the bottom of the table and have struggled to reinforce their squad during the transfer window.
Van Aanholt would be Allardyce's second signing of the window, following the arrival of Jeffrey Schlupp from Leicester City.