With Cristiano Ronaldo and Lionel Messi having rivalled each other for club and individual trophies for longer than a decade, it has now been claimed the Argentine perhaps helped Ronaldo improve as a player.
The superstar duo missed out on this year's The Best FIFA Men's Player award, finishing in second and third spot, respectively.
Ronaldo's former teammate Iker Casillas has now suggested that the Portugal talisman's rivalry with Messi likely played a role in him reaching the best version of himself.
"Obviously he (Ronaldo) is a good professional, he looks after himself, eats well, gives the necessary importance to rest also," Casillas told The National.
"So this is just a result of being what a footballer is. Other than that, he's also a great athlete. The reason is he's always hungry and always wanting to improve and better himself.
"Perhaps also his small rivalry with (Lionel) Messi has helped him better himself. But it's basically down to his professionalism and ambition; that has taken him to the top of the footballing world."
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Casillas was also asked how much longer he thinks the 35-year-old can play at the top level.
"I hope he can continue to play for a very long time. But, of course, football and its nature is what it is," the Spaniard added.
"We all know that everything must come to an end and time does go by for everyone. Hopefully we will be able to still enjoy his football for a long time, but it's difficult to say."