The Portugal star, who led his country to Euro 2016 success this summer, has no doubt he is "the best player in the world" and claims he is back in form after injury
Carragher's all-time best Man Utd XI
The Portugal international is one of the favourites to win the Ballon d'Or after winning the Champions League and Euro 2016.
And the 31-year-old's considerable self-confidence shows no sign of diminishing any time soon.
WATCH: Costa SLAPS mate after beating him on FIFA 17
"In my head, I am the best player in the world," he told La Gazzetta dello Sport. "And I am working very hard every day with the ambition to be the strongest. It is then up to others to judge me.
"I always want to improve myself. I am very motivated and I believe that is the key behind my success on the pitch."
The 31-year-old has endured a difficult start to the 2016-17 campaign after sustaining a knee problem in the final of Euro 2016, but feels he is nearing top form again after netting five goals in two games for Portugal during the international break.
'Ronaldo should have joined Arsenal - they didn't have the money!'
"I suffered a serious injury [in the final at Euro 2016] and missed two-and-a-half months, but I am feeling well now," he added.
"I am back to my usual best and I am ready to enjoy another spectacular season."