Ronaldo was named European Player of the Year earlier in the month and is favourite to win the World Player of the Year award.
“Cristiano is superb,” said Ferguson. “He has timing getting into the box, ability with two feet – and you would never associate a Portuguese winger with such magnificent ability in the air. He is like an old fashioned centre forward.
“There are a lot of things in his favour to go on and become a legend. The answers will come in the next few years.”
“When you have a star like this, a young player with such huge potential, they normally make an impact very early – which is what Cristiano has done,” he continued.
“Pele scored in a World Cup semi-final as a 17-year-old. Maradona played for his country at 17. Cristiano was 18. All the signs are the same.
“What you don’t know about him, but can say about Maradona and Pele, is that their careers lasted for a number of years.
“Pele played in two World Cup finals, as did Maradona. Maybe Portugal do not have the profile to get to World Cup finals, the same as Brazil and Argentina – so you have to judge him a different way.”