Keane is impressed with Ronaldo’s desire to improve and says his former Manchester United team-mate is the most intelligent player he has ever seen.
The Irishman played alongside the Portuguese at Old Trafford between 2003 and 2005, before the former joined Celtic in 2005.
A lot has changed since with Ronaldo winning a lot of trophies and etching his name as one of the greatest players the game has ever seen, but the only thing that remains the same is his desire of scoring goals.
At the age of 36, the former Real Madrid man is going stronger for club and country and Keane has lauded him for getting better.
“The most important part of Ronaldo’s set-up is his brain,” Keane said on ITV. “He’s the most intelligent player I have seen in my life. Obviously, I’m not going back to the 50s and 60s, but the guy loves scoring goals.
“His intelligence is amazing, how he plays the game, he doesn’t get involved in build-up plays but he’s got that trickery and arrogance which you need from the great players.
“The brain, the intelligence of the man, how he’s done it in different countries, how he’s looked after himself off the pitch as well.”
Keane added: “I can’t praise the man enough, he’s an absolute genius. “I love watching him. Just the brain he’s got, the cleverest player ever.”
Ronaldo scored five goals in only four games in Euro 2020 to help Portugal qualify for the knockout stages and equaled Ali Daei as record scorer in men’s international football history.
Portugal’s title defense, however, took a hit on Sunday in a 1-0 defeat to Belgium in Seville.