The former Metz player undertook a medical today which he passed with flying colours before a contract was reportedly laid down which is a five year deal with wages beginning at 800,000 euros per season with a transfer fee of 7 million euros plus added bonuses.
The French youth-international has been in great form this season in Belgium and as well as playing in the defensive midfield role, Koulibaly can also play as part of the central defence.
Napoli were also interested in signing the likes of Javier Mascherano of Barcelona and also Lyon's Maxime Gonalons but with Koulibaly playing the same position and moving for a much cheaper figure, it will
be unlikely that one of these two join in the Summer.
Koulibaly has made 35 appearances in all competitions this season (as per goal.com) with two goals, both of which came in the league for Racing Genk.