That's according to the Daily Mail's Neil Ashton, who claims the former Chelsea boss is in “advanced talks” to become Louis van Gaal's replacement at Old Trafford and has already instructed executive vice-chairman Ed Woodward to sell the duo.
Mourinho has already sold Mata once before, shipping him off to United back when he was in charge of Chelsea in 2014. Per Ashton, the Spaniard netted the club a cool £37 million then, and while his value has dropped since completing the move, he should still be a popular transfer target for a host of clubs.
As shared by Squawka Football, he has been the club's top creator by some distance in the 2015-16 campaign:
Squawka Football @Squawka
@DeGeaed Juan Mata has created more chances (36) in the Premier League than any other Man United player this season.2016-2-11 09:45:53
The decision to sell Fellaini shouldn't come as much of a surprise, and fans won't be too sad to see the Belgian go, either. The 28-year-old moved to Old Trafford from Everton in 2013 but has failed to replicate the form he showed for the Toffees since then.
He didn't make much of an impact under former manager David Moyes and has been used in a variety of roles throughout midfield and in attack by Van Gaal. The lack of consistency hasn't helped the Belgium international, but he has shown little to suggest he could turn things around with consistent playing time in a well-defined role.
Despite his struggles, Van Gaal has given Fellaini plenty of looks, and he has already started 10 Premier League matches this season, per WhoScored.com. Fans have practically begged the Dutchman to drop Fellaini, and some pundits have followed suit, including the Daily Mirror's Liam Canning:
Liam Canning @LiamPaulCanning
Tempted to breakdown after reading that Marouane Fellaini is still in the starting XI. Why is Schneiderlin still on the bench?2016-2-7 15:02:58
Fellaini's value on the transfer market may be limited, but he has impressed for the Belgium national team and earned his move to Old Trafford with some strong showings for Everton. If he's put in the right situation, he can be an effective player, and some club is bound to take a chance on the physical midfielder and make the Red Devils an offer.
The departure of Mata may be less well-received by the United faithful, but it also shouldn't come as a shock. Mourinho's decision to sell him in 2014 showed he wasn't a big fan of the Spain international, and things likely haven't changed.
Titanbet expects the feeling is mutual:
Juan Mata hearing the news that Mourinho is coming to Man Utd... https://t.co/mjOC90OXuw https://t.co/lHYSfU0qv12016-2-11 13:01:51
The 27-year-old winger is one of the best pure passers currently plying his trade at the Theatre of Dreams, and while his ability to create for others doesn't always show up in the statistics, he can be the type of anchor clubs need in midfield.
If he does become available, expect a number of clubs to pick up the phone and contact Woodward. An extended stay in the Premier League is an option, although he's just as likely to move back to his native Spain, and the Red Devils would probably prefer not to sell to a rival club.
The sales of Mata and Fellaini would free up even more cash for Mourinho to assemble the squad he wants to work with, and in all likelihood, United will be major players during the summer transfer window.
While there's plenty of young talent in the squad, Mourinho is expected to invest heavily, with the likes of Real Madrid's Cristiano Ronaldo and Everton's John Stones suggested as early targets, per Ed Malyon of the Daily Mirror.