Atletico Madrid president Enrique Cerezo said left-back Filipe Luis would like to leave the club.
Sources have told ESPN FC that Luis, 33, already has an agreement with Paris Saint-Germain and is now trying to get Atletico to agree a fee to permit the move.
Cerezo recognised Luis' desire to leave and said he and others at the club are trying to talk the Brazil international into staying in advance of the transfer deadline on Aug. 31.
"Filipe is a great player and a great person," Cerezo told Deportes Cuatro. "We are trying to convince him not to leave but players will ultimately play wherever they want to.
"We want Filipe to stay. I am optimistic and I think that he will stay. However, we will have to wait for the next few hours."
Luis played the full 90 minutes and was booked in the second half as Atletico returned to La Liga action with a 1-1 draw away at Valencia on Monday, and coach Diego Simeone said after the match that the defender will stay in Madrid.
Antoine Griezmann, Jan Oblak and Juanfran all also acknowledged that Luis has been tempted by an offer from another club.
Luis has won the Europa League twice in two separate spells with Atleti, as well as La Liga once and the Copa del Rey once. He also helped Atletico to the Champions League final twice and won the Premier League and League Cup double in his only season with Chelsea.