Benfica president Luis Filipe Vieira says the only hope of Joao Felix staying at Benfica is if they sell the teenager then take him back on loan.
Manchester United and Manchester City have been tracking the highly-rated 19-year-old, who looks set to move on this summer.
Felix has a release clause of €120million (£106million) and Benfica are resigned to losing Felix this summer.
Vieira told Benfica’s members: “We sit down with players and they say ‘president, I can earn five million euros, president, do not make me stay here.’
“Joao Felix had a release clause of 60million euros and we realised after two or three games that we must increase it to 120million euros.
“But it is Joao Felix and his family who will decide if he stays.
“If someone bids 120million euros it is not worth dreaming that he will stay.
“We are trying everything to ensure he stays. But the only way is if we sell him and keep him another year.
“If not, Joao leaves. There is no room to negotiate further. He doesn’t want to.
“How will Benfica negotiate with someone after he is given a proposal of 6million euros after tax?”