Clubs across Europe have coveted the Senegalese centre-back for years.
But Napoli have constantly searched for over €100m to sell their star defender, until now.
According to Il Mattino, the Neapolitan outfit has reduced that figure down to €45m (£39m).
The reason for this decision is Napoli are being forced to decrease their salary budget.
Koulibaly is a top earner at the club, pulling in €7m-per-year.