Ronaldo scored a hat-trick in the second leg of Portugal's play-off with Sweden on Tuesday to secure a 4-2 aggregate winand his country's place at the World Cup finals.
The Madrid star is one of the favourites for the Ballon d'Or, which has only been won by Messi four years in a row.
Ronaldo has scored 32 goals in all competitions for club and country so far this season and Messi - widely considered to be the best player in the world ahead of the Portuguese - is unsurprised by the former Manchester United man's remarkable form.
"I don't know if this is Cristiano's best moment, but he is always there, scoring goals in all the games and playing his part for his club and his country," the Argentinian said.
"He has been like that for many years. Whether he is at his best, or a bit below that, there is almost no difference."
Ronaldo, however, believes this season could be the best of his career, and is confident he can maintain his outstanding goalscoring form.
"Every season has been good," he told Marca.
"It's possible that with all the goals I'm scoring this is the best moment of my life.
"This could be my best season, but I think I'll always be up there."
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