The Portuguese captain is struggling with a thigh injury and has been ruled out of the warm-up match against Greece today.
International boss Paulo Bento admits he can’t put a date on the Real Madrid star’s comeback and will not any risks ahead of the tournament in Brazil.
Bento said: “Ronaldo will be with us against Greece but he will not play.
“We’re not going to set down a calendar for his return to competition.”
Ronaldo, 29, suffered an injury-hit finish to the season – completing just three of Madrid’s final 11 games
He sat out their last league game against Espanyol after pulling up during the warm up.
Ronaldo recovered to play the full 120 minutes in Madrid’s Champions League final win against Atletico Madrid.