The 19-year-old defender has enjoyed a rapid rise to prominence at Old Trafford after Louis van Gaal saw his options limited by a catalogue of injuries and suspensions.
McNair made his Premier League debut against West Ham in September and also started the following weekend's victory over Everton before being pressed into action again in last Sunday's Manchester derby following Chris Smalling's dismissal and an injury to Marcos Rojo.
On Tuesday, there was another notable milestone for McNair as he was named in a Northern Ireland squad for the first time, having been unavailable through injury when his country were last in action.
The youngster will now hope to make his debut for Michael O'Neill's men in their Euro 2016 Group F qualifier against Romania in Bucharest next Friday.
"When I was growing up, I always aimed to play for my country," McNair told United's official website.
"Obviously, as I've been playing for United, one of the biggest clubs in the world, I did hope I would receive the call.
"I'm really happy to get called up. I could have been involved last month for the Faroe Islands and Greece games, so it's great I've been recalled to join the squad for Romania.
"I want to keep working hard and try to play as many games as I can for United.
"Hopefully, I can break into the Northern Ireland team when I go. I do know a few of the lads - Corry Evans and Luke McCullough from United, of course. I know some others from the Under-21s, so I am looking forward to it."
