Carlos Queiroz's side open their Group G campaign against Côte d'Ivoire next Tuesday before further potentially tricky assignments against Korea DPR and Brazil.
But the Real Madrid star is not concerned by the magnitude of the task ahead. "I think Portugal is doing well. It's true that we play a very tough group stage but this helps us to improve even more," he said.
"Portugal is in a very good moment. It's true that the team has changed a lot. We will spend lots of time together before the tournament starts and that will help us to play a better World Cup this year. The first games of the group stage are very important."
Ronaldo believes his side and group rivals Brazil can count themselves among the six favourites for the showpiece event in South Africa. "Theoretically you can say that Spain, England, Italy, Germany, Brazil and Portugal are always the strongest candidates," he said.
"It will be a very special World Cup. Every player has the ambition to play such a tournament in order to showcase his abilities."