Yves Bissouma has signed for Brighton from Lille on a five-year deal.
Sky Sports News understands the fee is less than their club-record signing of Jurgen Locadia of £16m last summer. The deal is believed to be closer to £15m.
The Malian midfielder has made 47 appearances for Lille, scoring four goals in total as he becomes the club's sixth summer signing.
"I chatted with quite a lot of people who advised me it's a good league for my progression, and it's good to join a club like Brighton who know what they want, an ambitious club," he told the club website.
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"First of all I spoke to my agent, then I spoke to Bakary Sako who plays at Crystal Palace and Molla Wague, who plays for Watford. They both said a lot of good things about the Premier League.
"It's the dream of every player to come and play in the Premier League. They said it's different to Ligue 1 - but you see that on the TV.
"They said it's quite physical, quite difficult but it's the best league in the world, that says it all. To be a big player you have to prove yourself in the big leagues and that is what pushed me a bit to come here.
"I wanted to come and show what I can do in the Premier League and help the team move forward."
Bissouma has made 15 appearances for the Mali national team and played in the 2016 African Cup of Nations success.
He came on as a substitute in the 76th minute in the semi-final against the Ivory Coast and scored the decisive goal to seal Mali's place in the final.
Fulham were also keen on the 21-year-old before they signed Jean-Michael Seri from Nice earlier this month.