The 20-year-old was handed a place in the final five match-day squads of last season and made his full senior debut against Crystal Palace.
He continued to impress over pre-season with series of enterprising, solid displays in the middle and claimed his first senior goal against Valerenga.
And McTominay, speaking ahead of receiving a possible start against Burton Albion in the League Cup, was quick to heap praise on Mourinho for the impact he has had on his development.
“Things he does say stay between me and the manager, sort of thing, but a lot of it is help and advice, really,” he said.
“It’s all like when we go out on the pitch, what I can do better, things that I can improve on and he is brilliant for that with young players.
“He’s top – he’s perfect for a manager and that’s why he is manager of Man United. He’s a really good guy.”
No matter where McTominay’s career takes him, the Scot can always draw on what he picked up from Mourinho and feel grateful he worked under such a prestigious manager.
But this will not be running through his mind. The 20-year-old enjoyed a promising pre-season during which he showed poise, intelligence, an impetus to move the ball forward and a general sense of maturity that the Portuguese has taken note.
Supporters will be desperate to see him receive a chance to impress against Burton as Mourinho rests key players ahead of Saturday’s visit to Southampton.