Martials agent dropped a bombshell on Wednesday night when he confirmed that the 22-year-old was disillusioned with life at Old Trafford and would look to leave the club this summer.
Many at United are ready to block that request, but The Telegraph are reporting that Mourinho will give in to Martials demands if he can land a high-quality replacement.
Mourinho has lost faith in Martial despite a good first half of the season, with his game time significantly limited after the January arrival of Alexis Sanchez.
And, if the Portuguese coach can land either Real Madrid winger Gareth Bale or Chelsea star Willian, he is happy to green light Martials sale.
However, both Mourinho and the club are reluctant to sell to a Premier League rival, which could scupper their hopes of landing Willian if they will not permit Martial to go the other way.
Tottenham are also interested, and Martial has intimated that he would be prepared to move to White Hart Lane, though United would rather he was sold abroad.
Martials agent, Philippe Lamboley, told RMC: They want to extend [Martials contract] and do not want him to leave but we do not find agreement for several months.
I think that when Manchester United, which is the most powerful club in the world, does not find an agreement in eight months of negotiations, it is that it does not really want to make him an important player.
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