The Argentina international signed from Brazilian club Botafogo last summer and played 40 games for Diego Simeone's team in his debut campaign.
However, the former Atlanta United midfielder is rumoured to be unsettled in Madrid, and is open to moves back to wither Argentina or Brazil.
River Plate and Flamengo have both registered an interest in signing the 25-year-old, but the former's sporting director José Boto has distanced himself from an offer in recent days.
That does not mean an deal cannot be revived, but Boto was clear over his position over how much Flamengo are willing to pay, which is rumoured to be around €25M.
"We will no entertain or participate in bidding wars. Do you know how many transfers of €20M or more have been made in Brazilian football? Only seven!
"As the president of Flamengo, I have a responsibility to prevent the club from going bankrupt."