London - Premier League club Southampton smashed their transfer record on Monday to swoop for Lille's Morocco international midfielder Sofiane Boufal.
Boufal, 22, agreed a five-year contract with the Saints and is reported to have cost 16 million ($20 million/ 18 million euros).
Southampton's previous record signing was Dani Osvaldo, who cost 15 million from Roma in 2013.
"I'm very, very happy to sign for Southampton and I am really excited to play in St Mary's Stadium in front of the fans," Boufal told Southampton's website.
"Southampton showed big interest in signing me, and I can see that this club is the best place for me to continue my progression as a footballer.
"I hope I can achieve many great things with Southampton. It is a very good club, with excellent facilities, and I feel it is the perfect environment to continue my development."
Lille said earlier that only the medical visit could hold up the transfer.
Boufal underwent surgery in Qatar in May on his right knee cartilage. He will not be available to play until at least the end of the September.
Lille's deputy general manager Jean-Michel Vandamme told AFP: "We have been very transparent.
"They know everything and if they hire him it is on that basis," the Lille official added.
Boufal became one of the most highly-rated youngsters in France after moving from Angers in January 2015.
He attracted Southampton's interest after scoring 12 goals in all competitions last season to help Lille finish fifth in Ligue 1 and qualify for the Europa League, while also reaching the Coupe de la Ligue final.
"Sofiane is a player we have watched develop closely over the last few years, and we're thrilled to have him join the club ahead of what promises to be a very exciting season, with Europa League football on the horizon," Southampton's executive director of football Les Reed said.
"His excellent campaign with Lille last season meant a number of clubs were pursuing him to secure his services, but we're delighted that Sofiane sees Southampton as the best place for him to continue his development.
Claude Puel, who took over as Saints manager during the close-season, had plenty of chances to watch Boufal up close after spending the last four years as boss of Ligue 1 side Nice.
Boufal is Southampton's latest expensive recruit. They spent 10 million to sign Nathan Redmond from Norwich and 12 million on Bayern Munich's Pierre-Emile Hojbjerg.
Puel had been looking to add more firepower to his squad after Saints sold last season's top scorers Sadio Mane and Graziano Pelle.