The 17-year-old became the club's youngest starter in the Premier League era when Ole Gunnar Solskjaer handed him his full debut against the Bluebirds.
It was only the second time he began any game at Old Trafford, the other was with the Under-23s, against West Brom last month, and yet he took to the big stage instantly, even if he will feel he should have scored his maiden goal at senior level.
Starting wide in a fluid attacking front three with fellow homegrown products Marcus Rashford and Jesse Lingard, the England Under-18 international was unable to convert two early aerial chances and later had a deflected shot tipped onto a post by Neil Etheridge.