Sunderland have broken their transfer record to sign Didier Ndong from Lorient.
The midfielder joins the Black Cats on a five-year deal for €16m - £13.6m.
The 22-year-old arrives on Wearside having made 46 appearances for Ligue 1 Lorient since joining them in January 2015.
Sunderland's previous record transfer was the £13m they paid for Asamoah Gyan six years ago.
Ndong said: "I am very proud and happy to sign for Sunderland. This is a new adventure for me and to play in the Premier League is a dream come true.
"Maybe the Sunderland fans don't know me yet, but I promise that they will quickly discover that I will give everything for them and the club. It will be an honour to wear the Sunderland shirt and I will wear it with a true understanding of what it means.
"I am excited to meet everyone at the club, to see the stadium and of course the fans, who I have heard so many good things about. Today is the most beautiful day of my life."
A central midfielder the Gabon international previously played for Tunisian side CS Sfaxien, where he made 40 appearances, before signing for Lorient.
He has also has 18 caps for his country after making his debut for the national team in 2012.
Sunderland have also been linked with Norwich pair John Ruddy and Steven Naismith, with boss David Moyes managing both players at Everton.