Charis Mavrias is currently on loan at Panathinaikos but the Greek winger could still remain at Sunderland next season.
Panathinaikos are keen to make the move permanently over the summer but there is no option to buy from Sunderland.
The Black Cats though could change their mind and keep Mavrias at the club if the Greek attacking midfielder enjoyed a decent loan spell at Panathinaikos until the end of the season, as Sunderland manager, Gus Poyet said.
“It depends on him. He needs to play. Playing means performing well and seeing him improving. The only way to judge him is after five or six games of him playing regularly. At the moment, it’s been difficult,” Poyet quoted in Sunderland Echo.