Manchester United would reportedly have to pay £90 million to sign Napoli centre-back Kalidou Koulibaly in the January transfer window.
According to Duncan Castles of The Sunday Times, the Senegal international is the priority target for Red Devils manager Jose Mourinho midseason, as he seeks to improve the team's leaky defence.
However, it's reported United would have to pay a world-record fee for a defender if they want to prise the player away from the San Paolo.
"Napoli owner Aurelio De Laurentiis has made it clear that he considers Koulibaly central to a squad that lies second in the Italian championship and leads Champions League Group C ahead of Tuesday’s tie at Anfield," said Castles.