The Portugal winger, who joined Real Madrid from Manchester United for a world record 94 million euros in the close season, won the Ballon d'Or last year and was included in the 30-strong shortlist for the award formerly known as the European Footballer of the Year released on Sunday.
"Barcelona play better football (than Real), but why?" the 24-year-old told France Football magazine in an interview released on Tuesday.
"Because they have been together for several seasons, not two months. Barca are better than us today but the real question is who will be in front at the end of the season?"
The winner of the Ballon d'Or will be announced on December 1 and Ronaldo said that while Xavi and Samuel Eto'o were strong contenders, Argentina's Messi was likely to be the recipient.
"He's the favourite. He won the Champions League, the (Spanish) league. Why not him? If he wins it, he will have deserved it."
Arguably the world's finest player when on song, Ronaldo has been hampered by injury at Real and is struggling to recapture the form he showed at Manchester United.
He said, however, that he was hungry for more titles and felt he had picked the right club to do that.
"I must do again all I managed to do at Manchester, win the Champions League, league and cup titles," he said.
"I'm convinced I'm in the right club to do that. I'm starting a new career, I feel like a baby."
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