Besiktas coach Bernd Schuster is chasing Valencia defender Ricardo Costa.
The Portuguese only arrived in the summer, but is a €5 million target for Besiktas, says Super Deporte.
The 29 year-old signed permanently for Los Che at the start of the season from Wolfsburg, having had a six month spell with Lille in France.
Costa has enjoyed regular first team action at Valencia under coach Unai Emery.