Chelsea reached an agreement Wednesday to sign Napoli defender Kalidou Koulibaly for €40 million, The Guardian’s Fabrizio Romano reports.

Koulibaly reportedly agreed to terms on a five-year contract with Chelsea worth €10 million per season.

The 31-year-old only had a year remaining on his contract with Napoli.

The Blues sealed the deal for Koulibaly amid interest from Juventus, who reportedly held talks with the player’s representatives last week. Chelsea reportedly targeted Juventus center-back Matthijs de Ligt before making a move for Koulibaly.

The west London side needed a key signing in defense following the departure of Andreas Christensen and Antonio Rudiger. Koulibaly will add speed to manager Thomas Tuchel’s backline and compensate for 37-year-old Thiago Silva’s diminishing pace.

Tuchel wants to sign another central defender as well. The Guardian’s Jacob Steinberg reports a move for Manchester City’s Nathan Ake is expected to happen in the coming weeks. City are reportedly demanding at least £40 million for the Dutch center-back.

Ake and Koulibaly would form a dynamic three-man defense alongside Silva. As composed passers of the ball, Ake and Koulibaly can play out from the back and resist pressure from opponents. Koulibaly is also an aerial threat – a strength he shares with Silva – and excellent at timing challenges.

The Senegalese defender joined Napoli from Genk in 2014, making more than 300 appearances for the Partenopei. He became one of Europe’s preeminent center-backs in that time and played a key role in Maurizio Sarri’s popular possession-based system.