Manchester United will have to break their transfer record and may £130million to sign Kalidou Koulibaly.
Real Madrid, Barcelona and Chelsea have been linked with a move for the 27-year-old, according to reports in Italy, but United are believed to view him as a top priority.
Napoli president Aurelio de Laurentiis is not prepared to let him leave on the cheap, however, and is demanding a world-record fee for a defender, claim Gazzetta dello Sport.
The Senegal international has made 192 appearances in five years, scoring eight goals for Napoli.
He is currently on international duty as Senegal prepare to take on Madagascar and Mali.