Moises Caicedo was missing from Brighton training on Monday amid transfer interest from Chelsea.
The Ecuador international sat out Saturday's friendly with Rayo Vallecano and was again absent for Monday's training session.
Brighton chief exec Paul Barber insists Caicedo has been carrying an injury. However, BBC Sport says Caicedo is frustrated over Brighton's stand regarding transfer talks with Chelsea.
Chelsea have had offers rising to 80m rejected by Brighton, which now are demanding 105m to sell the midfielder.
Meanwhile, Caicedo missed Monday's training session and there is doubt that he will front up to the club's Lancing training ground on Tuesday.