Sevilla defender Jules Kounde's potential transfer to Chelsea is hanging in the balance as the La Liga side hold out for more than £43m (€50m) for the player.
A deal close to that figure has already been agreed but Sevilla are now thought to be asking for nearer the player's £68.5m (€80m) release clause.
The Spanish club turned down a €55m offer from a Premier League side last summer and are also keen to line-up a replacement before they let Kounde go.
The 22-year-old France international wants the Stamford Bridge move to be finalised before the transfer deadline and has not travelled with the Sevilla squad for their game at Elche on Saturday evening, staying in Paris.
A deal for Kounde is likely to be contingent on Kurt Zouma's move to West Ham, and the east Londoners have bought the centre-back for £29.8m.
The 26-year-old has signed a contract until the summer of 2025 after undergoing a medical on Thursday.
Sky Sports News previously reported that West Ham were keen to add defensive reinforcements and had targeted Zouma, who had fallen out of favour at Chelsea under Thomas Tuchel.
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