It was the 19-year-old's first goal of the season and Ten Hag has urged the forward to keep improving.
"You have seen at the start of the season we played him, his contribution was not good enough," said Ten Hag.
"You see always that 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.
"I want to see like today, he is entering the box in the right spot to finish.
"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."
There was again no place for Jadon Sancho, who has been banished from first team training following his public rift with Ten Hag over being left out of the squad for United's match against Arsenal in early September.
Sofyan Amrabat was handed his full debut after coming on as a late substitute in the 1-0 win over Burnley on Saturday and impressed despite starting the game at left-back in the absence of Sergio Reguilón.
"Sofyan is a player, and that is one of the reasons we signed him, where the team needs him, he will play and he can play in more positions," said Ten Hag.
"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, Amrabat, you see also others, they can contribute to our game and they will do."