Besiktas have reached an agreement with Sunderland to sign Dutch winger Jeremain Lens, beIN SPORTS Turkiye have reported.
The Turkish club saw a bid rejected for Lens on Friday having failed to meet the Black Cats' valuation for the player.
Now they have reportedly had an offer accepted and will enter discussions over personal terms with the 29-year-old.
Lens joined Sunderland from Ukrainian side Dynamo Kiev for £11m in 2015, making 23 appearances in all competitions in his first Premier League season.
The Netherlands international spent the majority of last season on loan at Fenerbahce as Sunderland finished bottom of the Premier League.
The Black Cats were expected to be willing to sell Lens if their demands were met, and manager Simon Grayson admitted on Saturday that he could be set for an exit.
"Obviously everybody is aware that we had a bid which we didn’t think matched his valuation but he was injured from the Bradford game and so he wasn’t available," Grayson told the Sunderland Echo.
"It depends how he goes in the next few days, he might not be here in a few days if a bid comes in."
Lens made 26 appearances in the Super Lig for Fenerbahce last season, scoring four goals and providing 11 assists for the title winners.
The pacy wide-man was originally keen on a permanent move to Fenerbahce, but financial fair play restraints mean that Besiktas are the club able to offer a return to Istanbul.