"The players, when they don't know if they are going to win or lose, by definition, they are under enormous pressure," he said, speaking as Brazilian organizers explained ongoing delays in finishing three of 12 stadiums.
The World Cup opens June 12 in Sao Paulo, with that stadium, and others in Curitiba and Cuiaba still incomplete. Another venue in Porto Alegre is finished but temporary structures are not finished, fallout from a battle over who pays -- FIFA, the local club Internacional or some level of Brazilian government.
"Of course, playing in your own country is an additional responsibility," Ronaldo said. "Brazilian people of course hope that all is prefect with Brazil winning. ... We have a great team, but the pressure is huge. But hasn't it always been very, very important for the Brazilian team as the favorite? So the Brazilian players are just used to this huge pressure."
A three-time winner of FIFA's player of the year award, Ronaldo is working as an "ambassador" for the local organizing committee. He compared Brazil's upcoming World Cup to the recent Winter Olympics in Sochi. He said people were wary of Sochi and were proven wrong.
"There was a lot of suspicion, the entire world was a little suspicious and then we saw it was a great success," he said. "In Brazil we have a small portion of people who are very suspicious, but the World Cup is going to be incredible to show the world our values and our culture."
Jose Maria Marin, head of the Brazilian Football Confederation, was even more blunt. He was quoted by Sao Paulo newspaper Folha de S.Paulo this week saying "we'll all go to hell" if Brazil fails to win the World Cup at home.
He repeated his views again Thursday sitting next to Jerome Valcke, FIFA's top World Cup official.
"What (Brazilian) people really, really expect in the World Cup is to win the championship," Marin said. "So we're still in purgatory. So either we all work together. ... or it's either to hell, or paradise or heaven. I'm confident we'll all go together to heaven."