Ronaldo left Real Madrid as their all-time highest goalscorer to join the Serie A champions earlier this summer in a 100-million-euro deal.
The 33-year-old did not manage to find the net in his first three Serie A games before he eventually scored his first goal for Juve against Sassuolo on September 16.
The Portuguese captain scored three goals and provided four in his last three league games, but Cafu still believes that the Italian topflight league will be much tougher for him.
“He will suffer a little in the Serie A because Serie A is a lot more difficult than La Liga in terms of the contrast in teams and in terms of the physical contact,” Cafu told ESPN.
He added, “But Ronaldo is always Cristiano Ronaldo. [He is the] best player in the world and will give a little more star power to Serie A.”