Both the Juventus superstar and Barcelona captain have amassed an incredible amount of silverware en route to establishing themselves as two of the best footballers of all time.
But Ronaldo and Messi have had their fair share of battles with defenders and some have proved far trickier than others.
Speaking to DAZN, Messi surprisingly snubbed the likes of Sergio Ramos and Diego Godin as his toughest opponent.
Instead, the six-time Ballon d’Or winner named his pick as Spanish right-back Pablo Maffeo, who he said proved to be an “intense” opposition.
“Man-marking doesn’t bother me — you know that there will be tough matches and it can be strange to always have someone around you,” Messi said.
“In truth, it hasn’t happened to me that often. It doesn’t bother me, but it is strange.
“Pablo Maffeo of Girona [was the toughest man-marker]. That was intense!
“I’ve never been one who complains. I think physical contact and kicks are part of the game.
“I get more annoyed when I play bad and I get a little more angry. But if I’m not [playing bad], it’s not a problem, it’s part of the game and I don’t take it personally.”
Ronaldo, meanwhile, has played in the likes of the Premier League, Serie A, La Liga and Primeira Liga in his club career.
The 35-year-old Portuguese superstar revealed his toughest opposition came in the form of former Arsenal and Chelsea defender Ashley Cole.
“Over the years I had some great battles with Ashley Cole, he does not give you a second to breathe,” Ronaldo told Coach Mag.
“He was such a tenacious player when he was at his peak, quick, tough in the tackle. You knew it would never be an easy game.”