Reserve goalkeeper Beto on Wednesday said Portugal can put their opening match horror show behind them and keep their World Cup hopes alive -- insisting the reason Ronaldo is playing is that he is fully fit.
Paulo Bento's side got off to the worst possible start in Brazil with a 4-0 drubbing from Germany in Salvador's Arena Fonte Nova on Monday as Thomas Mueller netted a hat-trick.
Real Madrid star and national captain Ronaldo, who came into the tournament on the back of knee and thigh injuries, failed to sparkle as his team sank to ignominious defeat in the Group G encounter.
On a night when nothing went right for the world's fourth-ranked side, Pepe was sent off for a head-butt and Fabio Coentrao sustained a thigh injury that rules him out of the rest of the tournament.
But Beto, in line to take over goalkeeping duties after first choice Rui Patricio suffered a tear in his thigh, said if Portugal played to their potential, they would beat the United States on Sunday.
"The best version of Portugal can beat the United States. We respect the USA as a very good team," he said
"They have grown up over the last years so we have to respect them but we believe in ourselves, we believe in our work, in our quality so we have to be responsible, we have to be in the best condition to win this match and we believe it."
The USA beat Ghana 2-1 in their opener and are on three points alongside Germany, meaning Portugal cannot afford another slip-up in the Amazon rainforest city of Manaus.
And Beto insisted that Ronaldo was fit to play despite ongoing speculation about his fitness.
"Ronaldo didn't leave (training) early. He finished his training at the same time as the rest of the players," said Beto.
"Cristiano is 100 percent fit to play. Every match he starts to play, it's because he's fit to play," said the goalkeeper, who plays his club football for Sevilla.
"He loves football but his body is the most important thing for him, to be fit, to be healthy so if he starts the match it's because he's ready, he's fit."
Ronaldo received a rock star's welcome as Portugal trained at the Estadio Moises Lucarelli in Campinas, outside Sao Paulo, on Wednesday.
As he jogged around the pitch, hordes of teenage girls screamed his name and fans pressed their faces against the wire fence to get a closer look at their hero.
The Ballon d'Or winner had a light workout for about 45 minutes before having ice applied to his troublesome left knee -- a precaution the medical staff have also taken in previous days.
The final matches in the group are on June 26, when Portugal play Ghana in Brasilia and the United States meet Germany in Recife.