The former Manchester United manager, who revealed the striker handed in a transfer request in May, says the forward is "back to what we always remember."
Ferguson's revelation in May that Rooney had handed in a transfer request sparked a summer-long saga in which the 27-year-old pushed for a move to Chelsea. United boss David Moyes reiterated his desire to retain the services of Rooney throughout the transfer window, and the England international has impressed since returning to United's first team after a preseason that was disrupted by injury.
Rooney netted twice in United's Champions League group-stage victory over Bayer Leverkusen on Tuesday, and Ferguson believes the forward has recaptured the form of his best years at Old Trafford.
"I thought Wayne was fantastic [on Tuesday]. He's got his energy back, his determination, his purpose to attack," Ferguson told MUTV. "Being a director, I'm delighted to see that. He's back to what we always remember."