Messi is the only player to win the prize, which recognises the best player in the world over a calendar year, since it became an official FIFA award back in 2010.
Ronaldo has finished second in two of those votes but, while Messi's 2013-14 campaign has been marred by injury, the Portugal international has been in superb form.
The 28-year-old attacker has scored 24 goals in all competitions for Real so far this term, and Ramos feels the former Manchester United man is now a level above his Argentine counterpart.
He told Movistar: "In previous years maybe not, but this year it is being demonstrated that, although he has always been seen as the best in the world, Messi is now a notch below Ronaldo.
"The Ballon d'Or has to be given to the best player of the moment."
The 23-man shortlist for the Ballon d'Or will be narrowed down to the three in December, with the winner announced on January 13 2014.
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