The Frenchman's contract runs until 2021 at Camp Nou, however the deal includes a £53million release clause, that United have already made clear that they would be prepared to trigger.
Despite the interest from Mourinho's side, Barcelona are assured that their centre-back will resist being tempted over to Old Trafford, and will instead renew his contract with the Catalan giants.
Given United's clear intentions to finance the transfer, Umtiti's entourage have used their interest as a bargaining power to guarantee a better deal with Barcelona before putting pen to paper.
Barca have drafted a contract that doubles the defender's wages and triples his release clause to deter interest from other clubs. The 'Azulgrana' are confident that Umtiti will agree to the new terms in favour of moving to Manchester.
However, for United, if they are unable to secure the French international, they are likely to shift their focus to Tottenham's Toby Alderweireld if they can agree on a lower asking price than the £55million Spurs are demanding.