The Barcelona and Real Madrid stars have been at the centre of a debate over who is the world's best player for a number of years, and the head of the sport's governing body beileves the competition is a great asset to the modern game.
Speaking after delivering a lecture in Geneva, the 76-year-old told reporters: "We face two men with a different game and perhaps contrasting personalities. This is a good thing for football. I find it something tremendous."
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"Football cannot have one type of player. Imagine there were two like Messi or two like Ronaldo. It would not work well. They are polar opposites and I believe it is tremendous for football to have personalities like them."
Both Messi and Ronaldo are favourites for this year's Ballon d'Or prize, a title which the Portuguese won back in 2008 but which has been held by the Argentine for the last three years.
Blatter explained that Fifa do not have final say on who is given the award, but that national federations are the ones responsible for voting.
He added: "Fifa do not choose who is best. It is not us who decides. "It is the federations that have the election and the president has neither the right to veto, nor the right to vote. It's something sporting."