Ronaldo has once again been overlooked for the Ballon D'Or in favour of Lionel Messi, who has now collected the prestigious award on four consecutive occasions, but the Portugal superstar, who won it in 2008 in recognition of his phenomenal 42-goal contribution to United's Champions League and Premier League double, remains Messi's closest challenger.
The United boss has no doubt the improvement he oversaw during Ronaldo's six-year stint at the English club has continued since his arrival in Spain, and he told Inside United: "Now you see the complete player. His decision-making, his maturity, his experience, plus all the great skills he has got, they all make him the complete player."
And, for the first time since he brought Ronaldo to Old Trafford, Ferguson will have to find a way of stopping the 27-year-old next month given Real Madrid lie in wait in the Champions League. It will not be an easy task.
Ferguson spoke to his protege in Manchester ahead of City's encounter with Real in November, then went to the Etihad Stadium to see the winger take the Blues apart in the opening stages of what ended up being a 1-1 draw.
The Scot added: "Maturity brings many things.
"When I went to see them play against City, some of his decision-making in terms of passing was brilliant. One-touch passing, good crosses.
"In the six years we had him, you just saw his game grow all the time, and he was a fantastic player."
Ferguson is trying not to think about the best way to combat Ronaldo, preferring instead to concentrate on the players in his own squad and exactly who will be fit for the first leg at the Bernabeu on February 13.
"Obviously you hope that when you draw Real Madrid it's in the final," he said. "It will be a big, big event - we're the two most high-profile clubs in the world and I think they will be great games."