"The thing that has impressed us all is his knowledge," said Ferguson.
"I noticed him the other night directing players who were much older than him.
"That is a nice sight to see from a young lad of 19, considering his English is not perfect.
"He missed the pre-season because of the Copa America, so it took him some time to get his fitness levels up. But he is there now.
"We knew there would be a time when we had to see what he is capable of. Maybe, because of the injuries, that time has come a bit earlier than we might have expected. But he has taken to the job very well."