Speaking at a news conference on Friday, Scolari was typically vague about whether the winger, who missed training on Friday, would recover for the match in Gelsenkirchen.
"He may play, he may not. I know, I don't know. I have no idea if he will be able to play or not. I believe he can, yes, from what I have seen of his recuperation, but also maybe he doesn't play," he said.
Earlier on Friday, team spokesman Afonso Melo said Ronaldo was training separately but was still not totally fit.
"If he's not 100 percent fit, Scolari won't play him," he said.
