The Brazil legend has outlined his favourites for the tournament, but feels Portugal can cause an upset in South America.
The Selecao legend, who was part of the team that won the 2002 tournament, has been detailing who he feels are the favourites ahead of the Brazil tournament.
Rivaldo, who had decorated spells with the likes of AC Milan and Olympiacos, is perhaps best known for his legendary exploits with Barcelona and his national side.
Speaking to Goal.com, the former attacking midfielder played down Luiz Felipe Scolari's side as favourites and instead preferred to heap the pressure onto rivals Argentina and Spain.
However, Rivaldo also claimed that Paulo Bento's Portugal should be considered as dark horses.
"Spain and Argentina are the two strongest teams at the moment," he said. "As we know there are eight world champions who are involved in this tournament, and with all of their experiences, they have all got my respect.
"But Portugal potentially could make an upset."
Ronaldo is currently nursing knee and thigh injuries, but returned to training on Saturday morning, and is expected to be fit for Portugal's opening game against Germany.
Scolari's side begin the competition with a mouth-watering opener against Croatia on Thursday, and while Rivaldo believes that the side will beat the European nation, he does not think La Selecao are among the strongest teams in the competition.
He added: "I think Brazil will do their best. I know there will be a pressure before the first game. With all my respect, I’m confident we will play a good game and take a victory over Croatia."
Brazil are in Group A with Croatia, alongside Mexico and Cameroon, and signed off in their warm-up games with a 1-0 win against Serbia in Sao Paulo on Friday night.
Despite being booed off at half time, Fred scored just before the hour mark to give Scolari's men back-to-back wins heading into the tournament.
What do you expect of Portugal at this summer's World Cup?