Having secured a much-needed Premier League victory at Burnley on Saturday evening, the Red Devils ran out comfortable 3-0 victors against Roy Hodgson’s south Londoners on Tuesday night.
The 19-year-old began United’s first two matches of the season, but this was the first time he was named in the starting line-up since the defeat to Tottenham five weeks ago.
“You have seen at the start of the season we played him and then his contribution was not good enough,” manager Ten Hag said of the Argentina international.
“But he also had some good actions. You see always he is a threat in the game even when he is not playing that well.
“He has to learn when he does his job in defending he will always have his moment and he will always be decisive because he has great qualities.
“As well, it’s not only off the ball. But I want to see like today, he is entering the box in the right spot to finish.
“But I think it is quite normal for a player of his age that there is space for a lot of improvement.
“Everyone likes him, the fans like him, the team likes him, I like him but we also have to demand from him and push him because he can act on a very high level but he has to show it every day.”
United made seven alterations, as did Palace, ahead of Saturday’s Premier League reunion at Old Trafford.
The on-loan Tottenham full-back’s absence meant Sofyan Amrabat filled in there on his first start for the club, before stepping into midfield at half-time.
“Sofyan is a player, and that was one of the reasons we signed him, where the team needs him, he will play and he can play in more positions,” Ten Hag said.
“Every player has his best position but he gives a certain dynamic in the game. We have seen today but also for him and many players, we just started.
“That process was a little bit interrupted by the many injuries we have because when you can play a long time with the same team then you get routines, the players learn each other and it’s more automatic.
“You see Mason (Mount), Amrabat, you see also others, they can contribute to our game and they will do.”
As for Palace, Roy Hodgson had no arguments with the result as his side made a meek Carabao Cup exit in the third round.
“I thought we were well beaten, basically,” said the Eagles boss, who saw Dean Henderson go off injured on his debut at former club United.
“I thought they attacked better than we did, defended the few attacks we were able to mount quite comfortably.
“As a result, unfortunately, you tend when that happens to only be looking at one possible result and that was the result they came up with.”