Besiktas have confirmed the arrival of Jeremain Lens from Sunderland for an undisclosed amount.
The Dutch winger joins recent signings Pepe and Alvaro Negredo at the Turkish Super Lig champions having spent last season on loan at Fenerbahce.
He was reportedly expected to sign a new deal with Aykut Kocaman's side but joined Besiktas after failing to agree terms.
The 29-year-old former AZ, PSV and Dynamo Kiev winger netted four times in 26 matches last season, while creating a further 12 goals.
He flew into Turkey to complete his deal and watch his new team in the Super Cup against Konyaspor, with the match kicking off on Sunday evening.