Rodri is one of seven Man City players nominated for the prestigious gong, including talismanic striker Erling Haaland.
The Norway international netted 52 goals in his debut season while guiding City to a historic treble, including their first ever Champions League triumph.
Rodri has been nominated having played a key role in City's treble victory, including a match-winning goal in the Champions League final against Inter Milan.
Despite that, the Spaniard is backing Messi for the ultimate prize, which is up for grabs in Paris on October 30.
"I think a certain Leo Messi is going to take it, "Rodri told COPE.
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"Haaland is also a very large figure and has merits."
Messi led Argentina to their first ever World Cup in Qatar last year, bagging seven goals and three assists in the process.
He also helped Paris Saint-Germain win their second straight Ligue 1 title before making the free transfer to Inter Miami, where he immediately helped the Major League Soccer side to their first silverware.
And Rodri admits he just hasn't got the individual profile to compete with Messi and the other 'monster' stars nominated.
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He added: "I know it's an individual award with a lot of marketing.
"Among the monsters I'm with, of course, I lacked marketing, like Xavi and Iniesta.
"I worry about the things I can control, which is the collective awards."
Since plying his trade stateside Messihas helped guide Inter Miami to glory in the Leagues Cup.
He could not, however, help his side earn a place in the play-offs after missing the last five matches of the campaign through injury.
Should the Barcelona legend pip Rodri and Haaland to the gong, it would mean a record-extending eighth Ballon d'Or for the 36-year-old.