Real Valladolid are pushing to keep Sandro Ramirez until the end of the La Liga season but have yet to reach an agreement with Everton.
Sandro's loan will end on Tuesday but the Blues are locked in negotiations with the La Liga club over a fresh deal, says the Liverpool Echo.
Everton will continue to pick up the striker's wages in full when he returns and so are keen to strike a deal for the 24-year-old.
But discussions have yet to reach a conclusion which suggests the Spanish side could be looking to renegotiate the terms of the original deal.
Valladolid have six more league games scheduled with the last of them, against Real Betis, due to be played on July 19.