"I'd love to be 110 percent and but I am 100 percent and that is enough to help my team," the Real Madrid striker said.
The Portugal forward and FIFA player of the year was seen earlier this week walking away from training with ice bags on his knee. He wore a bandage on the knee during Sunday's practice at the match venue, the Arena Fonte Nova.
"Obviously I wish I did not have any pain, but that is impossible," Ronaldo said. "I don't think there's ever been a day without pain."
Ronaldo played in his team's Champions League final on May 24 despite earlier doubts about his fitness and scored a penalty to complete Real Madrid's 4-1 victory over city rival Atletico.
Both German and Portuguese teams have stressed that Portugal is not just about Ronaldo. But Portugal's hopes of upsetting Germany will hinge on Ronaldo's ability to score.
"The importance of having in the team a player like Cristiano is enormous, but this does not mean we have to be world champions," Portugal coach Paulo Bento said Sunday. "All 23 players have to be like a compact team in order to achieve a good result."
Ronaldo said "one player is not a team.
"I can make a difference but I am here to help the team."
Germany goes into the match with recent history on its side. Germany has won the last three tournament matches against Portugal: a 3-1 win in the match for third place at the 2006 World Cup; a 3-2 win at Euro 2008 and a 1-0 victory in their opener at Euro 2012.
"Obviously history has been positive for Germany. But Real has beaten Bayern Munich (in the Champions League semifinals) and maybe this will be the year to change the history and Monday would be the best day for it to happen," Ronaldo said. "It's a new tournament, new players, our team is good, we have confidence."
That said, the talismanic forward was wary of raising expectations too far.
"We must be humble. It's a difficult start for us," he added. "We are playing one of the favorites and one of the best teams. I personally and the entire team is very motivated and we want to enjoy the tournament."
France benefits from first key use of goal tech
Porto Alegre, Brazil • France benefited from the first decisive use of goal-line technology at the World Cup on Sunday when the team was awarded a goal in its match against Honduras, which the French went on to win 3-0.
With France leading 1-0, Karim Benzema's shot hit the far post and rebounded to Honduras goalkeeper Noel Valladares, who fumbled the ball into the goal.
The seven video cameras trained on the goal established that the ball had briefly crossed the line by a few inches, alerting the referee on his watch with a flashing "GOAL," before the ball was pushed out again by Valladares.
An own goal against Valladares was awarded, making the score 2-0 to France in the 48th minute.
But there was some confusion seconds before when the system showed replays of Benzema's shot hitting the post with the verdict "NO GOAL" before continuing to show the actual goal. The change infuriated the Honduras players, some of whom remonstrated with referee Sandro Ricci, while Honduras coach Luis Suarez bickered with France coach Didier Deschamps. At the end of the match, they hugged and made up.
"Well, I wasn't angry because they accepted the goal. I was angry because they didn't accept the goal. The first decision was 'No goal' and then the machine said it was a goal," Suarez said through a translator. "So I don't know what to think. That's the point. If the technology sends a clear message, then I don't understand how the system can say it's a goal first and then 'No goal.' What is the truth?"
Deschamps had some sympathy with the Hondurans over the images that were broadcast by organizers.
"The only problem was that they showed an image on the screen that didn't correspond to the goal," the France coach said. "They showed the ball hitting the post when the ball hadn't crossed the line yet. The ball was clearly over the line after the goalkeeper had fumbled.
"Obviously, I can put myself in their position and, of course, they were very angry and so were the fans because if you're going to show an image it should be the right one."
As for the use of technology, though, he said: "It's a very good thing."
The system is being used for the first time at a major international football tournament.
France also benefited from the first ever Golden Goal at a World Cup when defender Laurent Blanc scored late into extra time in the second round against Paraguay in 1998 the year it won the tournament.
Benzema scored France's two other goals.
Around the World Cup
Brazil • Striker Hulk left practice Sunday in Teresopolis, Brazil, due to a muscle injury in his left leg, but said he expects to play Mexico on Tuesday in his team's second World Cup match.
Hulk practiced for less than 15 minutes before leaving the field. He said the injury wasn't serious and "hopefully" it wouldn't keep him from playing in the next match.
"I felt a small discomfort and decided to leave as a precaution," Hulk said. "I was already thinking about the next match, it's only two days away and in the World Cup you don't want to miss any match. I hope to be ready so I can help the national team again."
Hulk said he had the injury before the opening win over Croatia, when he was replaced late in the match, and felt it again after a few shots on goal on Sunday.
He walked off the field without a limp, but then sat down on a bench and lowered his head in apparent dismay. Hulk, who plays for Zenit in the Russian league, put his hand on his left leg when team medical staff arrived to treat him.
A few moments later he went to the locker room accompanied by one of the team's doctors.
"I was feeling down when it happened because you always think about the worst," Hulk said. "But then I talked to the doctors and they told me that it wasn't anything too serious. I'm going to undergo treatment and hopefully I'll be able to play."
The Brazilian federation said Hulk wouldn't need additional tests and would travel as planned with the rest of the squad to the northeastern city of Fortaleza later Sunday.
"At a World Cup you have to overcome every challenge," Hulk said. "We prepare our entire lives to fulfill our dreams of playing in the tournament. I'm feeling well."
If Hulk is ruled out, 21-year-old Shakhtar Donetsk striker Bernard would be his likely replacement. Chelsea's Ramires is also an option.
Brazil had been injury free since it started its World Cup preparations in late May, but Sunday was a tense practice session in Teresopolis, outside Rio de Janeiro.
Bernard stayed on the ground for a few moments after a foul by David Luiz, and the defender was later hurt in a challenge by midfielder Luiz Gustavo. Both players were down briefly but recovered.
Coach Luiz Felipe Scolari ended the training session after the hard contact between Luiz and Gustavo.
Netherlands • A Dutch newspaper says that Arjen Robben ran faster than any footballer recorded on his way to scoring the final goal in the Netherlands' 5-1 drubbing of Spain at the World Cup.
De Telegraaf says it clocked winger Robben at 37 kilometers per hour (22.9 mph) in his blistering breakaway for his second goal in Salvador on Friday. According to the paper, that broke the previous known speed record of 35.7 kph (21.8 mph) by Arsenal's Theo Walcott.
Olympic champion Usain Bolt reportedly reached a top speed of 44.72 kph (27.7 mph) when he set the 100-meter world record of 9.58 seconds.
Croatia • Angered by published photos showing them bathing nude at their training complex's swimming pool, Croatian players are refusing to speak to World Cup reporters.
"They are determined that they will not speak to the media," Croatia coach Niko Kovac said. "I don't know if this will last until tomorrow, or until we are at the World Cup."
The pictures from paparazzo photographers were published by Croatian media.
"I can't force them to change their minds after what you have done to them and their families," Kovac said.
A news conference scheduled for Monday at the Croatian camp near Salvador was canceled.
Colombia • Colombia complained to FIFA on Sunday about its security detail in Sao Paulo, saying police escorts are intentionally slowing down the team's World Cup movements.
Brazil's Justice Ministry responded by saying it has taken "adequate" measures to guarantee the team's movements during the tournament. Colombia's football federation has asked FIFA to make changes to its security detail.
The team's press officer, Mauricio Correa, said there have been "repeated incidents" of delays, including the team's arrival at Mineirao Stadium on Saturday. Colombia beat Greece 3-0.
Correa said the security detail, which is overseen by federal police in Sao Paulo state, is intentionally going too slowly at 20-25 kph and the situation is bothering Colombia's staff and players.
The Justice Ministry said all teams receive the same treatment.