Manchester United legend Roy Keane warns the club's fans to not expect too much from Kobbie Mainoo.
The midfielder impressed in his Premier League debut, starting in a 3-0 win over Everton on Sunday.
While the 18-year-old looked at home in the heart of United's team, Keane believes he will have to work much harder in future games.
"Unbelievable. Listen, don't want to get too carried away but I'm sure we will. He looked like he always had time on the ball today. His decision making, in terms of when to go long, when to go short. Off the ball as well," Keane told Sky Sports.
"What a phenomenal performance. Obviously, I know the club thinks highly of him. But then the build-up to the game today, coming to Everton, for the manager to put him in, he obviously must trust him and the staff around the place.
"Listen, good luck to the kid, he was outstanding. It's a great start for him. Let's hope he stays injury free, he gets a run of game for Man United because he looked like a Man United type player today. Nice and brave, lot of courage, loved watching him.
"United are some way off the top teams. They seem happy with sixth, they should be competing with the best teams. They go to Newcastle next week, we'll see what United turns up."