The Real Madrid superstar has been plagued with persistent leg injuries recently and - after sitting out Portugal's first World Cup warm-up friendly with Greece - will also miss the encounter with Mexico later on Friday.
Portugal have just 10 days to go before they face Germany in their first Group G fixture, and head coach Bento stated that preparations for the match cannot depend upon whether his captain Ronaldo is fit.
"The situation is evolving and our expectations are evolving constantly," he said.
"When he's ready to play is a decision that will be made just like any other player, regardless of who it is. I'm not at liberty to discuss at full length the situation. As soon as he is ready to train, we will make that announcement.
"We have to prepare for Germany regardless. The decision of if he will play and when is up to me, the player and the doctors. Ronaldo is not the only good player we have.
"But it's also true I can't change your (the media's) opinions. We'll continue with the work we've been developing until now. The only issue is when he will be able to join us and to play."
Ronaldo is not Bento's only injury concern, with defender Pepe (leg) and midfielder Raul Meireles (thigh) also unavailable for the Mexico game.
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