The 16-year-old made his fourth senior appearance for the club on Thursday (AEDT), coming off the bench for the final 10 minutes a 4-0 win over Wolfsberger.

And he made a telling impact almost immediately, hustling a defender out of possession to set up Carlos Vinicius for the hosts' fourth goal.

Mourinho could barely contain his delight at the rapid progress of a player whose quality reminds him of another major talent he once helped develop.

"He is a diamond, a kid with incredible potential," the Portuguese said.

"He has worked many times with the first team and that gives him a different personality. He is still 16, 17 soon [in March] and I believe next season he will be a first-team squad player because he has a lot of talent.

"He is going to be a fantastic player and I hope everything around him goes well. He is a striker, a number nine, I have been playing him from the sides similar to Marcus Rashford and he is very clever.”

Mourinho praised Scarlett even further in his post-match media conference, revealing the teenager is already splitting his time between the senior squad and Under-23s.

"Dane has incredible talent. I don't want to speak too much because tomorrow I arrive in the building and the kid's boss is going to kill me," he added.

"I don't want that so I don't want to speak too well about him. I just want to say that he will be 17 next month and I want him to be part of the first-team squad next season.

"So this season he is there and here, goes to training sessions with us and matches with the kids of his age and trains there.

"Next season he has to be a first-team player. Immense talent. Very good physical development.

"He's very good, he's going to be very good. I hope that nothing is going to destroy that potential. He must have feet on the ground and head on his shoulders because he has a fantastic talent."