Levante midfielder Jose Campana is being linked with Atletico Madrid.
Atletico can make an emergency signing outside the transfer windows after losing Thomas Partey to Arsenal.
Campana has a release fee of €60m, but Levante president Quico Catalan told Radio Marca that he would sell him for half.
"If Atletico came to me I'd sit down to negotiate, but I'd never sell him for less than 30 million euros," said the president, leaving the door open for the player to leave.
"I think it's natural that Campana wants to grow. He told me to my face in my office, but his behaviour has been exemplary."
This is his fifth season with Levante after playing for Palace, Nurnberg, Sampdoria and Porto.