Ronaldo, 34, is enjoying a fine debut season in Serie A since joining Juve from Real Madrid last summer. The Portuguese attacker has scored 19 times in the Italian top-flight, with a further four goals coming in the Champions League.
Ronaldo, who won four of his five Champions League titles with Real Madrid, ensured his side remain in contention for this year's European crown with a star performance in Turin on Tuesday.
He therefore drew level with old rival Lionel Messi on a record eight Champions League hat-tricks, but Mendes is in no doubt who is better.
"He is the best player in the history of the game and he proved it against Atletico Madrid," Mendes said to Gazzetta dello Sport of his client.
"Without him, Real Madrid wouldn't have won that much, he was the leading light and he is the best player in the history of Real Madrid.
"I am sure he will make the difference in Italy as well. He will make history at Juventus.
"Cristiano is epic, incredible, divine."
Juventus will find out their quarter-final opponents when the Champions League draw is made on Friday. The remaining teams in the competition are Ajax, Barcelona, Liverpool, Manchester City, Manchester United, Porto and Tottenham.