​Manchester United have reportedly opened negotiations with Napoli for Senegalese defender Kalidou Koulibaly, ahead of a potential £90m move in the January transfer window.

Since moving to Napoli in 2014, Koulibaly has established himself as one of the world's finest midfielders. Former manager Maurizio Sarri helped develop the defender, and he is now one of the most wanted centre-backs in Europe.

Paris Saint-Germain v SSC Napoli - UEFA Champions League Group C

News of the meeting between ​United and ​Napoli comes from ​The Times, who claim that Jose Mourinho's side are keen to organise a January transfer for the defender. However, they have been quoted a price of over £90m, with Napoli reluctant to allow their star centre-back to leave the club.

Koulibaly is said to be keen on making the move, even encouraging United to contact the ​Serie A side.

United's search for a central defender during the summer was well documented, with the club reportedly targeting the likes of ​Toby Alderweireld, Diego Godin and ​Jerome Boateng. However, they failed to land any of their primary targets, much to the frustration of Mourinho.

SSC Napoli v Paris Saint-Germain - UEFA Champions League Group C

The Portuguese manager is also said to lack confidence in United's willingness to meet Napoli's asking price, with many reports suggesting the Red Devils are reluctant to authorise any expensive deals.

The club are believed to prefer a younger defensive target, meaning they may steer clear of a big-money move for 27-year-old Koulibaly.

It has been suggested that United are unimpressed with Mourinho's transfer targets. He was insistent that the club signed Brazilian midfielder ​Fred during the summer, beating rivals ​Manchester City to his signature, but he is yet to impress at Old Trafford.

Manchester United v BSC Young Boys - UEFA Champions League Group H

United have suffered greatly with defensive injuries in recent weeks, with the likes of ​Eric Bailly and Victor Lindelof forced into periods on the sidelines. They currently sit 6th in the ​Premier League, having kept just two clean sheets since the start of the season.