Sunderland have completed the signing of Greek winger Charis Mavrias from Panathinaikos.

The 19-year-old has signed for a fee in the region of £2.5m, penning a deal which will keep him at the Stadium of Light until 2016.

Mavrias had impressed at the Greece Superleague side ever since making his debut in 2010, and he went on to make 51 appearances during his next three years with the club.

The midfielder, who has represented Greece on two occasions, becomes Paolo Di Canio's 10th signing of the summer.