The World Player of the Year Ronaldo, aged 29, failed once more to train with the rest of his teammates ahead of Friday's friendly with Mexico in the United States.
Portugal begin the Brazil showpiece against strongly-fancied Germans on 16 June but it is growing more likely that they will do so without their star player and talisman.
The Real Madrid forward has a left thigh injury and tendinitis in the knee of the same leg, and has been struggling for fitness for several weeks – and even if he is free of injury, it looks increasingly unlikely that he will be match-fit.
Bento told reporters: "The situation is evolving and our expectations are evolving constantly.
Franck Ribery has returned to training with France
"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."
Bento added: "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."
As it looks to be bad news for Portugal, France received a boost ahead of the tournament as Franck Ribery returned to training with Didier Deschamps’ squad.
The 80-cap winger, who plays for Bayern Munich, has been struggling with a back problem and has been following an individual training programme, but returned to join his team-mates on Friday morning.
Assistant coach Guy Stephan told French radio station RTL: "His progress is going quite well, he's doing a lot better but he still hasn't trained with the team. All the most specific and specialised care possible has been taken, and is still being taken. He is training with the team on Friday. If everything goes well, he will be there.”
