The 20-year-old midfielder had previously trained with the first-team ahead of a UEFA Champions League tie and obviously did enough to earn himself an opportunity with the senior squad.
For Weir, it was a big moment in his career and something he had been working towards as his main aim for this year at Man United.
“The goal is to get in the first team,” he told ManUtd.com back in October.
“I try to do my best and impress Warren Joyce and the coaches plus the first-team staff in training. Hopefully, I can get there. I just try to do as well as I can by keep pushing and striving towards that first team.
“I just want to get on their radar. You never know how things will work out – I look at Paddy [McNair], Willo [James Wilson], Andreas [Pereira] and Jesse [Lingard] and just hope I can do that too.
“I’ve been mainly on the left this year but I can come in off the flank and play as a false winger, if you like, which is quite popular in the modern game.
“I can also still play as a central midfielder who can make runs forward and hopefully get back as well. I can play that narrow left-winger role and do a job for the team while also scoring some goals.”
Weir follows in the footsteps of the likes of Andreas Pereira, Tyler Blackett, Paddy McNair, Cameron Borthwick-Jackson and a few other youngsters who have been given their first taste of a match-day experience by van Gaal.
For all his shortfalls as a manager this season, that’s one thing which has stuck with the traditions of United but there are plenty who would argue they’d prefer a stronger, deeper squad rather than a thin one which is almost forced to use youngsters when injuries kick in.