Cristiano Ronaldo is certain to play Portugal's crunch FIFA World Cup™ opener against Germany despite a lingering knee problem, said goalkeeper Eduardo on Saturday.

Ronaldo took a full part in warm-ups in front of the watching media but he was careful not to put his full weight on the strapped knee as the squad went through some jumping drills. All eyes have been on the FIFA World Player of the Year's recovery from thigh and knee problems, despite his return to play 65 minutes of Portugal's final warm-up game against the Republic of Ireland this week.

The Real Madrid forward, whose form and fitness will be vital to Portugal's chances, sparked new fears over his knee problem when he had it iced after training on Thursday. But he looked able to run freely in a series of short sprint drills in which he practised his famous step-overs without the ball.

Afterwards, Eduardo echoed team-mate William Carvalho's comments a day earlier when he said Ronaldo would be fit and ready for Monday's game in Salvador. "Cristiano is training well, he's training hard and we are sure he's going to be 100 percent to help us and to have an excellent game," Eduardo said.

Of course, Ronaldo is good. You're talking about the best player in the world.

Eduardo, Portugal

Monday's Group G clash in Salvador is a re-run of Portugal's UEFA Euro 2012 opener against Germany, when they went down 1-0 to a second-half Mario Gomez goal.

Eduardo said motivation was high for Ronaldo and the Portugal squad to erase a "disastrous" 2010 campaign which ended in the last 16 at the hands of eventual winners Spain.

"He's healthy and he can't wait to start this tournament. He's determined and he wants to play to the limit, like all of us, with an immense will to win and give our best. You can see it in training, in the hotel, and that's certainly going to reflect in the tournament," he said.

Despite their ranking of fourth, Portugal struggled in qualifying and they needed Ronaldo's four goals in the two-legged play-off against Zlatan Ibrahimovic's Sweden to book their place in Brazil. Eduardo admitted that the "best player in the world" was a key element in a team that will also face Ghana and the United States in Group G.

"Of course, Ronaldo is good. You're talking about the best player in the world. It's like the other good players in the other teams that can make a difference," he said. "We're ready for anything, but of course with Cristiano it's better for us. Of course we are a group, a lot of good players and nobody wins alone. But of course with Cristiano it's better for us."