Sunderland have signed Netherlands midfielder Jeremain Lens from Dynamo Kiev after the clubs agreed an £8m fee.
Lens, 27, worked with Black Cats head coach Dick Advocaat at AZ Alkmaar and PSV Eindhoven.
Sunderland finished 16th in the Premier League in 2014-15.
"My qualities are that I'm fast, I can score goals and I can create chances," said Lens, who has joined on a four-year contract. "I followed the team after the arrival of Advocaat."
He added: "I watched the derby against Newcastle United and the supporters were really amazing, so I've got a good impression of the fans and I hope they support us in the same way during the new season."
Advocaat's side are in the United States and lost 1-0 to Sacramento Republic in the first match of their pre-season tour.
The Black Cats are set to play Mexican side Club de Futbol Pachuca in California on 17 July before an away match against Canadian Major League Soccer team Toronto FC on 22 July.
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