Logically, he is not lacking in confidence - as he confirmed in an interview with Spanish TV show La Sexta.
"I believe I am the best player in football history, no one has been better," said Ronaldo, who also admitted that he could have played for Barcelona.
"The numbers say I am the most complete footballer that has ever existed. People can like Messi, Maradona, Pele... and I respect that, yes, but I am the most complex and the numbers say that," he said.
"In the history of football, I haven't seen anyone better than me. I tell the truth from the heart," said Ronaldo, who has netted an incredible 923 competitive goals in his career.
He also boasted about his list of strengths. "I'm fast, strong, I score goals with my head or my left foot, no one has ever been more complete than me. I am the best player in history. I really believe that."
The Al Nassr striker, who has also donned the shirts of Sporting Lisbon, Manchester United, Real Madrid and Juventus during his prolific career, also admitted that he could have headed to Barcelona before moving to England. "I could have played for Barça. They tried to get me when I was at Sporting. They wanted me, but a year later Manchester United came along."
It was Barcelona, whose colours were defended by his career rival Lionel Messi, who were his biggest rivals throughout his days in La Liga.
But in his own words, Ronaldo enjoyed the matches against the Blaugranas. "I loved playing at the Camp Nou. They booed me, they insulted me and I loved it!"
In a wide-ranging interview, the owner of six Ballons d'Or also commented on the most recent award - which was won by Manchester City midfielder Rodri.
"Vini (Vinicius Junior) deserved to win the Ballon d'Or, but I'm not surprised - it lacks credibility," Ronaldo said, before adding words of praise for the Brazilian: "He won the Champions League and scored goals."