Ronaldo has had a stunning start to the World Cup, scoring four goals in Portugal’s first two games.
The 33-year-old Real Madrid star has reinvented himself as a striker after spending the majority of his career on the left wing.
But Ferdinand says Ronaldo has always had the movement of a centre-forward throughout his career.
“It’s terrible to play against someone like that, especially when the ball’s wide,” he said on BBC One.
“If you watch him, he was a winger, but his movement in the box when the ball’s wide is that of a centre-forward.
“He has (turned into a poacher) and as a defender when someone stands still, I can see it, I can control him.
“But these guys, the top-level players, they move, they keep you on your toes and you don’t know where you are.”
Cristiano Ronaldo is currently leading the way for the World Cup Golden Boot.
And Ferdinand reckons that will be something he is definitely targeting.
“He’ll be looking at them stats there, looking at goals, looking at what other people do,” he added.
“All the other striker’s I’m sure would be the same. In tournament football you look at everyone else for inspiration. ‘I want to replicate that’.”