Real Madrid are reportedly preparing to make a big offer for Napoli's Kalidou Koulibaly.

The Spanish giants intend to make a move for the Senegalese defender next summer, according to Calciomercato.

The report claims that Madrid see Koulibaly, 28, as a long-term replacement for 33-year-old Sergio Ramos, whose contract expires in 2021.

Napoli president Aurelio De Laurentiis is thought to be keen on selling Koulibaly as well as Dries Mertens in order to rebuild the squad.

Koulibaly is a long-term target of Manchester United and currently possesses a price-tag in the region of £100m, although that would be reduced if Napoli do not achieve Champions League football for next season.

The Italian giants are currently struggling in seventh in Serie A after 14 games.