Ole Gunnar Solskjaer was over the moon with the contribution of Brandon Williams after the teenager finished his full Manchester United debut on the winning side.
Williams, 19, and 18-year-old James Garner were two surprise picks for United's Europa League visit to Partizan Belgrade on Thursday.
Playing at left wing-back, Williams completed all 90 minutes of the Group L match while Garner started alongside Scott McTominay in midfield before being withdrawn for Andreas Pereira with nine minutes remaining.
A single strike from the penalty spot from Anthony Martial was enough to give United all three points, in the process sealing their first away victory since beating Paris Saint-Germain in March.
And Solskjaer singled out his two teenage starters for special praise, admitting he was particularly impressed with Williams' assured display.
"They did excellent," Solskjaer said of the pair after the game.
"I thought Jimmy just grew and grew into the game, became better and better. And Brandon was, for me, man of the match.
"He's been fantastic in the few games he's played, the boy has no fear, he's as brave as a lion and he got us the win.
The Norwegian manager added that he was frustrated that his side failed to build on Martial's opener and finish the game off, but drew comfort from a solid defensive display marshalled by young Williams.
"In games like these when we get the first goal, we need to learn when to get the second and when to get the third," he said.
"But Brandon has an absolutely great attitude, the boy is gonna be a top, top player.
"I thought today we had loads of opportunities to make sure we're in a comfortable lead, but didn't play that pass forward.
"We defended really well in the box, especially. I think we showed some grit in that respect.
"We could've defended better up front, we should have stopped them, they pushed us back, we need to get more intensity in our pressing. But proud and we kept another clean sheet."
United are back in action on Sunday, when they will be hoping for more joy on the road away to Norwich City in the Premier League.
