The teenager, signed from Atalanta for £37m, was introduced as a half time substitute for the Europa League round of 16 clash with their Italian rivals, following the injury of Anthony Martial.
Diallo, 18, made an instant impact for Ole Gunnar Solskjaer’s side, with Bruno Fernandes picking out the youngster’s darting run that unlocked the Milan defence.
Owen Hargreaves has hailed the ‘fabulous’ impact of Amad Diallo following his stunning goal
Diallo, 18, made an instant impact as a half time sub, scoring a brilliant header on Thursday
With the ball hanging in the air, the Ivorian adjusted his body to flick a header over the onrushing Gianluigi Donnarumma and give the Red Devils the lead at Old Trafford.
Solskjaer has been reticent to throw Diallo into first team action, with the likes of Dan James and Mason Greenwood ahead of the youngster at present, but former United stars Scholes and Hargreaves heaped praise on the teenager’s impact.
‘Fabulous to see a young player come on and have an impact on the game.,’ Hargreaves said on BT Sport.
The teenager adjusted his body to meet a Bruno Fernandes ball and flick it over Donnarumma
And Hargreaves said the ‘fabulous moment’ will be ‘huge for him’ after Thursday’s game
‘This is what Bruno [Fernandes] does best. That is an amazing run for a young kid. The execution of that.
‘A good pass and a good run beats a defence. That is a fabulous moment for the young man.
‘Nice to see him come on and have a really good impact in a big moment. To get a big goal will be huge for him.’
Scholes explained the technique used by Diallo was ‘brilliant’ in engineering an opportunity from a difficult ball from his Portuguese team-mate.
The £37m man has had limited game time but has left United fans excited about his future
‘You have to adjust to where the ball is coming to him,’ the former midfielder said.
‘That is the best he could have done with that ball. Great run from Diallo. He has had to improvise, that back header was brilliant.’
United were unable to hold onto their one-goal advantage, with a late headed goal from Simon Kjaer leaving the tie in the balance heading into the second leg at the San Siro.