Powell slipped quietly into Old Trafford while the focus of attention was on the acquisition of Shinji Kagawa and Robin van Persie.
But Ferguson believes Powell, 18, has 'a gift' and is genuinely excited about the youngster.
He said: "You won't see much of him at the moment because he has to come to terms with our training.
"He is getting there, though, and when he does he will be ready for the squad.
"He is only 18 but he has a gift and can achieve great things. We tracked him for a long time at Crewe.
"He will easily take to life in the top division."