The Belgian midfielder will be out of contract the upcoming summer and as such will be allowed to sign with foreign clubs in January should no agreement be made ahead of time.
According to The Sun, Fellaini is asking for a pay-rise to better match his new-found value and his teammates salaries.
The Sun appear to know his exact demands with Marouane reportedly asking for 130k in weekly wages to tie him down to the club.
Mourinho has been in full praise this season for Fellaini and has regarded him as an unsellable player meaning a contract should be tied up soon.
An Old Trafford source told The Sun: “There is a fear that Marouane will only stay here with a major pay increase.
He is on good money already, but feels he has a worth. They are in a difficult spot with him out of contract next summer.
The club already took out their 12-month option to extend his deal back in January, so it’s proving difficult.”
Jose will certainly be furious that things weren’t sorted out earlier and quicker as to not distract his players during a crucial time in the season.
United have been remarkable in the early stages of their Premier League campaign but should the contract renewal get out of hand, it may prove a costly distraction.
Fellaini will also definitely feel he deserves a pay rise after his incredible performance against Crystal Palace in which he scored a brace.
The player is currently away on international duty with his country but Mourinho will surely hope this matter is dealt with before all his players return.
The international break has already proved itself to be a momentum killer previously, as the Red Devils struggled to draw with Stoke City the last time the players left for their countries.
With Jose’s men since recovering, he’ll be hoping that his players can continue their good form this time around without any disturbances.
Fellaini himself will also surely want this business dealt with swiftly in order to keep his head in the game and to truly nail down his starting XI spot.