Rooney has been deployed in a variety of roles in recent years, with the England international often shifted out wide or into a deeper position.
But with Ronaldo having moved to Real Madrid, Ferguson needs to find another regular source of goals and he believes Rooney will relish the challenge.
The United boss said: "I don't think the responsibility of getting more goals will affect Wayne at all.
"He's got the mental strength for all that kind of thing. He's proved that time and time again.
"He will be used as a central striker this season. He goes on these bursts of goals.
"Last season I think he hit seven in a row at one point - but if he can do that more consistently over the season, he will get to 25 and above.
"But Wayne is a totally different type of player to Ronaldo.
"I don't think you can compare them, they are such different types."