Question marks over the fitness of the FIFA Ballon d'Or holder have dominated Portugal's build-up to the tournament.
The Real Madrid forward has been plagued by thigh and knee problems for several weeks, but is expected to feature from the start against Germany in a game both sides can ill afford to lose.
With Ghana and the United States representing potentially tricky future opposition, the European sides in Group G know an early defeat would severely dent their respective hopes of making the last 16.
Midfielder William Carvalho, among those to have delivered positive updates on Ronaldo's progress in recent days, believes Portugal are capable of impressing against Joachim Low's men.
"During the training sessions we talk about how we will play with each other, but we simply have our strategy and I am sure that in the first match you will like how we play," said Carvalho in a press conference.
Nevertheless, Low's side are fancied by many to make the latter stages of a fifth successive major tournament.
However, the match-winner two years ago, Mario Gomez, was left out of Low's 23-man squad after a season wrecked by a serious knee injury.
As a result, Miroslav Klose is the only out-and-out striker in Germany's party and the veteran Lazio man can equal a notable record by finding the net against Portugal.
