Panathinaikos winger Charis Mavrias has arrived in Sunderland for a medical with the Premier League club.
The Black Cats have already signed 10 new players this summer as Paolo Di Canio embarks on his first full season at the Stadium of Light.
The 19-year-old Greek is understood to be on the verge of a £2.5m move, according to Sky Sports News.
Mavrias penned his first professional contract with Panathinaikos in 2010 after graduating from the club's youth academy.