There is a clause in Jules Koundé’s contract that would allow him to leave for free if Barcelona don’t register him before the end of the transfer window, according to journalist Adrià Soldevila.
Barcelona were able to register their new signings before their La Liga opener against Rayo Vallecano last weekend.
Koundé was the only player not registered in time for the 0-0 draw at Camp Nou.
With just two days to go before the game against Real Sociedad, Barça are still unable to register the French centre-back.
The registration of the defender depends on the club agreeing a significant salary reduction with one of the highest-paid players at Camp Nou, as reported by Mundo Deportivo.
The talks with Gerard Piqué and Sergio Busquets to alter their contracts have not progressed as the Catalan club had hoped.
Two of the main candidates to leave this summer and reduce the wage bill are, Memphis Depay, who is close to joining Juventus, and Pierre-Emerick Aubameyang, who Chelsea are looking to sign.