Ander Herrera has enjoyed a quietly impressive season to continue his rise from fringe player to one of the first names on the manager's team sheet.
Louis van Gaal never seemed convinced by Herrera's qualities and, perhaps because of his struggles to nail down a first team place, lacked conviction and consistency under the Dutch boss.
The Basque midfielder was again one of United's best players against Watford and has developed into one of the most complete midfielders in the league.
Anthony Martial was voted man of the match with Juan Mata and Eric Bailly also excellent, but Herrera was immense again and doesn't get the recognition he deserves.
Deployed alongside the world's most expensive player Paul Pogba, Herrera was instrumental in keeping United ticking and quietly pulled the strings from his deep-lying engine room role.
Mourinho appears to slowly be phasing Michael Carrick out of his team, and so Herrera has picked up the baton of our most important player.
He intercepted wayward Watford passes, broke up attacks and moved the ball forward to set United moving.
Herrera always look to play the ball forward, and although it may not seem the most difficult thing in the world, it sets the tempo for the side.
Pogba may be a superb player in his own right, but his style contrasts vastly to that of the quietly efficient Herrera.
The young Frenchman possesses more strings to his bow in terms of his passing range, power and physical ability but often tries the spectacular instead of keeping things simple.
There's one area of Herrera's game that needs work on: his finishing.
His goals-per-minute ratio under LVG was decent in his more advanced position but under Mourinho he's been utilised in a more withdrawn role and so does not push forward as much.
His long range efforts from distance invariably find the Stretford End but, if he keeps this level of performance up, we'll gloss over that.
Herrera may not be the snarling, in-your-face, raging bull Roy-Keane esque leader that we perhaps associate with a United skipper, but he has all the credentials of a future captain.
Softly spoken but yet not afraid of getting stuck in, Herrera speaks with a passionate love of the club and its fans rarely seen in a foreign export.
He has an understated ability to inspire those around him, is known as a vocal organiser both on the field and in the dressing room and only N'golo Kante can top him for work rate and energy.