The youngster was handed a rare Premier League start by Louis van Gaal following injuries to Phil Jones and Marcos Rojo.
Despite dominating possession at Stamford Bridge, United lost the game 1-0 thanks to a strike from potential PFA Player of the Year Eden Hazard.
However, it was McNair who was singled out for praise by fans and pundits alike after putting in a strong performance alongside Chris Smalling.
And one man impressed by the 19-year-old is former United star Paul McGrath, who reckons that McNair is in line to become an Old Trafford hero.
I thought he was incredible against Chelsea. He showed a maturity level that I would never have shown at that age
Paul McGrath
Speaking to the club's website, McGrath explained: "I thought he was incredible against Chelsea. He showed a maturity level that I would never have shown at that age.
"If a space opens up in front of you as a defender and you know you're quick enough to go through it without getting caught, then you should go through it.
"He did that a few times at Chelsea and even tested Courtois with a shot. He seems to be very comfortable with the ball at his feet."