The Manchester United player was injured in the team’s 1-0 win over the Netherlands and was not present at his side's training sessions on Thursday or Friday.
"We don't know about Ronaldo," Scolari told reporters.
"We're still awaiting word on his fitness.
"I'll decide if he plays just a couple of hours before the match," said the Brazilian.
While the 2002 World Cup winning coach would be without key midfielders Deco and Costinha through suspension he was confident of their replacements doing the job.
"Costinha and Deco are special players," said the coach who is aiming to become the first in World Cup history to win the title with two countries.
"All our squad players are special, those who play in their place are also special players and we trust them."