The 25-year-old scored the only goal of the match in Monday's FA Cup clash with Aston Villa, as the Red Devils advanced into the fourth round of the competition.
McTominay has again been a vital player for Man United this season, making 22 appearances in all competitions, scoring twice in the process, including a goal against Burnley in the Premier League.
The Scotland international has now made 155 appearances for the 20-time English champions since breaking into the first team, and he has been tipped to lead the side in the not too distant future.
"He is an Academy boy, [and] his energy is amazing," Rangnick told BBC Sport. "He's now also started scoring goals, and also with some leadership skills. I wouldn't be surprised if, in a couple of years, he would be the captain of this team."