Crystal Palace manager Sam Allardyce has praised the imminent arrival of new signing Patrick van Aanholt, describing the defender as his "saviour" during the pair's time together at Sunderland.
The Black Cats announced on Friday morning that a fee has been agreed, reported to be in the region of £14m.
In his weekly press conference, Allardyce confirmed that the Dutchman is undergoing a medical ahead of finalising the details of the deal.
The Palace boss hailed the left-back's qualities, claiming that the 26-year-old was a crucial part of Sunderland's successful survival bid in the 2015-16 campaign.
"Van Aanholt was a major saviour in our run at Sunderland last season. Major part of that success story," Allardyce told reporters. "Goals and assists contribution was massive. His defending improved under me and he listened to advice."
Van Aanholt, who joined Sunderland from Chelsea in 2014, has scored three goals this season.