The Portuguese star believes his Barca rival has "a great future" ahead of him.
The Catalans signed the 22-year-old from Santos for an estimated 87.2 million euros and he has scored nine league goals and picked up eight assists in his first 25 games for the club.
Despite Real Madrid's intense rivalry with the reigning Liga champion, Ronaldo thinks that the Brazil international will blossom into one of the world's elite stars.
"I see Neymar as a great player," he told SporTV News. "I think in recent times he has proven be a player with a great future. His adaptation into Barcelona was not the best, he had some problems at first, but I have no doubt that he has the potential to be one of the best players in the world or even the very best player in the world."
The 29-year-old was then asked about his country's hopes for this summer's World Cup in Brazil and he feels Portugal has been drawn in the hardest group in the competition, facing Germany, Ghana and USA.
"We're not the favorites," he said. "But we will try to enjoy it. We know that we have a complicated group, in my opinion it's the strongest in the World Cup. We have to go step by step. We have a big game against the Germans first and then we play Ghana and the United States to pass the group stage. Then we'll see."