As a motivator of men, Rooney believes the Scot cannot be equalled and will never be surpassed.
Roo revealed: "Some of his team talks... you walk out on the pitch and you say to each other 'How good was that?'
"For the British players who understand him, it is incredible. It's more difficult for the foreign lads to understand.
"But it gets you right up for the game and I don't really think that is something that can ever be replaced."
Ferguson signed Rooney from Everton in August 2004 and then, just over a year ago, made sure he stayed at United when the England striker claimed he wanted out.
Rooney, 26, added: "For me, he's a great manager and a great man. He is the reason I signed and a big reason why I'm still here."