The youngster, who made his senior debut back in May, attracted praise for a disciplined, energetic performance against Sevilla in the Champions League.
And he played a fundamental role for Jose Mourinho once again against the champions, covering every blade of grass in midfield to provide a vital piece of urgency to accompany the stability and innovation brought by Matic and Paul Pogba respectively.
Speaking soon after the game, Matic was quick to hail the way McTominay went about his business in the middle against Antonio Conte’s side.
“He is amazing,” he said. “He is 21 and to play like that and control the game like that is impressive. He will be a big player for Manchester United.”
“I like him because he is a very nice guy and he doesn’t have a problem to ask before the game something and I am always there to help him.
“When I came to Manchester I saw within a few days he would become a top player.
“He is working very hard, but I don’t want to say too many things about him because he is still very young. But he deserves all the good things.”
McTominay’s display was not, as some are trying to suggest, in the same category as the job Ander Herrera did on Eden Hazard last April, but in a way it didn’t need to be.
He hounded the Belgian all game, losing concentration only once for Chelsea’s goal, but how well he stopped him from playing is beside the point.
Rather, the value of McTominay’s display at Old Trafford came in its fearlessness; never once did he look overshadowed or cowed by the sight of Conte’s side, but rather actively encouraged by the size of the challenge. He seemed to relish the battle from start to finish, dropping to his knees at full time to let out a huge, guttural roar of delight and relief.
The main thing to take away from McTominay’s game was not how well he controlled Hazard; supporters should instead derive immense joy from the way another academy product looked right at home on the biggest of stages.