Sunderland are casting their net far and wide as they scout players across Europe.
The Black Cats are understood to have had representatives watch Olympiacos draw 1-1 with Besiktas in the Europa League, with Besiktas midfielder Tolgay Arslan the player they were keeping tabs on.
The German-born midfielder, 26, has made 29 appearances this season and has long-been linked with a move to the Premier League.
It comes as fresh reports in Turkey suggest Besiktas are keen on Sunderland winger Jeremain Lens, who is currently on loan at their rivals Fenerbahce.
Should Sunderland step up their interest in Arslan in the summer, Lens could potentially be used in a swap deal as the 29-year-old does not look to have a future on Wearside.
Sunderland are bottom of the Premier League, six points from safety, with their status as a top flight club hanging in the balance.
But the precarious league position hasn't stopped the club scouting potential summer signings, with Sunderland also keeping tabs on Serbian wonderkid Luka Adzic.
As reported by the Echo, the Black Cats sent scouts to watch the 18-year-old Crvena Zvevda youth prospect in last weekend's Eternal Derby against bitterest rivals Partizan Belgrade.
But they face a battle to land the youngster, with the likes of Arsenal and Manchester City also keeping an eye on Adzic’s progress.
A left winger, who can also play as a striker, Adzic is seen as one of the brightest lights in the Serbian game.
The youth international broke into the Red Star first-team squad at the back end of last season, but did not make his first appearance until November.
Since then he has come off the bench five times, scoring twice in the Serbian SuperLiga.
His impressive cameos have not gone unnoticed, with Sunderland just one of a host of European sides to send scouts.
Sampdoria, Sporting Lisbon, Anderlecht, Bordeaux and Alaves are also understood to have sent scouts to report on Adzic.