France Football are set to reveal the winner of world football's most coveted individual award next Thursday, with competition between the era's dominant players as fierce as ever.
Ronaldo has arguably failed to match his old rival in terms of virtuoso performances but a stunning goalscoring run in the knockout stages inspired Madrid's run to back-to-back Champions League triumphs and they also pipped Barcelona to top-flight glory in Spain last season.
Speaking ahead of Saturday's trip to Athletic Bilbao, Zidane showed little regard for the prospect of it being a close race between Messi and his star man.
"Ronaldo's human, just like us but he is very different at times. He has no limits, really," he said.
"The fact that he's going to win his fifth Ballon d'Or explains that. It's just amazing.
"He deserves it as well. I'm sure Cristiano is going to win his fifth Ballon d'Or.
"It doesn't surprise me. He wants more and more. He has the ambition to win a sixth or a seventh
"I think he deserves the award for the season he's had."
Ronaldo won the Best FIFA Men's Player in London in October, with Messi and PSG forward Neymar finishing second and third respectively.
But last month images appeared online of a supposedly leaked version of the front cover of December's France Football magazine, which suggested Messi would be the victor this time around and move their career Ballon d'Or tally to 6-4 in his favour.