Napoli have completed the signing of Kalidou Koulibaly from Genk, while they have also confirmed that Roberto Colombo and Giandomenico Mesto have renewed their contracts with the club.
The Partenopei announced the news via a statement on their official website, with Koulibaly -- who has penned a five-year deal -- saying he was delighted to be joining the Serie A side.
"I am very happy to be playing for Napoli, an important club with a great project," he said.
"I am ready for this adventure and I can't wait to get started working with my new teammates so I can experience the [Stadio] San Paolo."
Napoli also announced they had renewed the contracts of goalkeeper Colombo and right-back Mesto.