Michael Carrick said Kobbie Mainoo is a "real joy" to work with after the England international caught the eye in Manchester United's 4-0 thrashing of Sabah on the Red Devils return to the Champions League.
On his first Champions League start, Mainoo completed 81 passes in just 64 minutes on the field to continue his revival under Carrick.
Largely overlooked by Carrick's predecessor Ruben Amorim, Mainoo played a major role in United's upturn since the former midfielder took charge in January.
"He's a fantastic player, I think it's pretty obvious to see," said Carrick.
"The way he's performing, playing that little bit deeper really and connecting the attacks, starting the attacks and having a massive influence on our games.
"He's a real joy to kind of have, he wants to learn, he wants to improve, he wants to listen and he expresses himself on the pitch. It's great to see."
United reinforced their midfield with the signings of Youri Tielemans, Andrey Santos and Carlos Baleba in the transfer window.
Yet, Mainoo's importance was underlined when he did not start on the opening weekend of the season in a 2-0 defeat at Hull.
Mainoo missed most of pre-season after he was part of the England squad that reached the World Cup semifinals, albeit he did not play a single minute in the tournament.
Since he has been restored to the starting line-up, alongside Tielemans and captain Bruno Fernandes, United have scored 11 times in three games.
"I think through the middle of the pitch we've played some good football at times," added Carrick.
"I thought some of our attacking play was fantastic."