The 20-year-old made his debut in the competition as a late sub in the away trip to Benfica, a 1-0 win, but started the game at Old Trafford against the Portuguese champions to fulfil a childhood dream.
Two other academy graduates were in the squad to keep a record going of 3,883 matches of Man United having a homegrown player in the matchday squad, a record that stretches back to 1937.
Mourinho is often criticised for his refusal to lend chances to young players, but came out all guns blazing after Tuesday’s 2-0 win.
“Scott [McTominay]? Even more fantastic with a manager who never gives a chance to a young guy
“In Chelsea, [I selected] the youngest player ever to play in the Champions League, I think, in Dominic Solanke,” Mourinho reminded reporters.
“Again, with a manager who never gives a chance to young guys. I’m very happy for Scott, [he has] great stability and great personality.”
When Mourinho arrived at United he was quickly questioned on his youth policy, and defended himself then with some dubious claims.
His policy is if you’re good enough you’re old enough, but also the reversal. Young players have to earn Mourinho’s trust. Marcus Rashford has done that, and McTominay is beginning to do so as well. Axel Tuanzebe is beginning to get Mourinho’s trust, also.