Man United are still looking for their first Premier League title since Sir Alex Ferguson retired in 2013.
"We're very lucky to have him because he's the best in the world, I don't care what the critics say. He is the best goalkeeper in the world, by far, and he will show it again".
The Portuguese said, "Valencia, Smalling, Bailly and Shaw, they are probably the ones to start the season". When you are the best goalkeeper in the world and you don't make those unbelievable saves, everyone is going to talk.
"I have plans to make him train the most most possible times with us, because that increases his evolution".
Curaçao-born Chong, who's played global football for the Dutch underage sides, joined United from Feyenoord in 2016.
"Technically, he's very good, tactically he understands the game and he understands his position, but by the physical point of view, when the game gets into contact situations, he's in trouble, he's fragile, he's still a kid".
United began their summer schedule with a 1-1 draw against Club America at the University of Phoenix Stadium on Thursday night.
But Pogba may have to wait a while longer, Mourinho has confirmed like Antonio Valencia will be Manchester United's new club captain, after Michael Carrick announced his retirement from the game at the end of last season.
Mourinho is missing a number of first-team players for the club's pre-season tour of America, and that has resulted in members of the second-string being given the opportunity to feature across the pond.
"I am very relaxed about him".
Chong's debut for the first-team was followed by Mason Greenwood - two years his junior - when he came on for the impressive Luke Shaw with 14 minutes remaining. He wants to learn and he listens a lot in training. "I know the club is making the effort but the USA authorities have their processes".