Sevilla are reluctant to sell Jules Kounde to Chelsea unless they pay a fee close to the €80m release clause, Goal reports.
The Blues have agreed personal terms with Kounde, but they are now in negotiations with Sevilla over his potential transfer.
The Premier League giants recently made a €35m offer for the central defender with Zouma acting as a makeweight.
The offer has been snubbed by Sevilla, who are reluctant to lose the Frenchman unless they receive a sum close to the buy-out clause.