The Mexican came off the bench to score a hat-trick as the Red Devils came from 2-0 down at Villa Park to win 3-2 in the Premier League.
"As I have been saying for the last few weeks, he's fresh as he had a good summer break and it's made a difference to him," Ferguson told Sky Sports News. "
When he came to us two years ago, that's what we're seeing again today and, when you score a hat-trick, you pick yourself. I think he'll be playing next week.
"He does his natural thing. He's fantastic in the penalty box with his movement, his quickness and being in space and that has got him three goals today."
United lead the Premier League table with 27 points from 11 matches.