Sunderland have completed the signing of Lorient midfielder Didier Ndong.

The 22 year-old moves to the Black Cats for €20 million, reports L'Equipe. He becomes the richest transfer in Sunderland history.

The Gabon international has signed a five-year contract after flying into Wearside last night.

Ndong had been tied to Lorient until 2019.