The Scotland star has established himself as a regular for the Red Devils over the past year, having been handed his debut by Mourinho in 2017. The Portuguese manager was axed by United in December 2018, although McTominay has continued to impress under the tutelage of current boss Ole Gunnar Solskjaer.
Speaking about the early stages of his United career, the youngster said he owes a lot to Mourinho for the faith he showed in him, per Sky Sports:
"Jose is very special to me. He still keeps in contact with me now and keeps in touch after some games.
"He'll always have a special place in mine and my family's heart because he's the one who brought you in, he was the one who trusted you, he was the one who had belief in you. I owe a tremendous amount of credit to him because if it wasn't for him I might not necessarily be sitting in this seat."
Here is more of what the United star had to say about his former coach:
The 22-year-old has been a mainstay of the United midfield this term, starting all eight of the team's Premier League games.
In the recent clash with Arsenal, the Scot scored his first goal of the campaign, lashing home a fierce strike from the edge of the box to break the deadlock in a 1-1 draw:
Per Squawka Football, McTominay was outstanding in that match at Old Trafford:
The youngster is beginning to show why Mourinho was keen to integrate him into the first-team setup when he was the United boss.
While McTominay may lack the natural creative talents Paul Pogba is blessed with, he adds a presence to the hub of the team when performing well. The Scotland international can win tackles and carry the ball forward into dangerous positions.
To become a true box-to-box midfielder he needs to improve his productivity in the final third. Football writer Stefan Bienkowski said recently he believes McTominay is more effective when he's forward-thinking:
Mourinho clearly had belief in McTominay, and the midfielder has earned the trust of Solskjaer too. Given United are depleted in this part of the pitch, the Red Devils academy graduate will have a huge role to play this term.
The team have struggled so far this season, and they sit in 12th position in the table after eight games. Runaway Premier League leaders Liverpool are up next for the Red Devils on Sunday, and you sense the team will need a colossal performance from McTominay in that encounter if they're to earn a positive result.