Chong created Juan Mata's goal for the 1-1 result and impressed his manager.
Mourinho told MUTV: "He came with the intention to show and in a moment where we have no strikers on the pitch - Martial was the only one and then he left - so we need people to create, to have some initiative which he did.
"The action for the cross in the goal was a beautiful action. He was enthusiastic, he was confident to play. Of course, physically, he has his limitations and when he has one more touch and he allows that body contact, of course, he loses for everyone but when he makes the ball move and attacks people one v one he has qualities. He is a good kid."