Marouane Fellaini is just one player that Besiktas hope to sign ahead of next season, according to board member Metin Albayrak.
The 29-year-old took time to settle at Manchester United under a succession of managers but has found an unlikely backer in Jose Mourinho, who has brought the best of the Belgian this season.
But Fellaini, who is currently sidelined with a knee injury he sustained while playing for his country, is out of contract at the end of the season.
Albayrak was reported by Turkish media as saying: "Fellaini is on our list, we have made efforts to sign him but not just him.
"He is not the only player we scouted, our scouting team watched 20 games live this week.
"Transfer plans never end, we are always working. We are keeping tabs on several players.
"The club has plans for Turkey and Europe, there are negotiations. We want to make the signing for the winter transfer window or for the end of the season."