The first of two South America v Europe semi-final duels kicks off at Belo Horizonte's Mineirao Stadium at 5pm (2000 GMT), with Brazil bidding to reach their first World Cup final for 12 years.
Brazil's campaign has been given a surge of emotion after the fractured vertebrae suffered by Neymar in the quarter-final win over Colombia.
Crowds of yellow-shirted fans thronged streets outside the Mineirao chanting Neymar's name as the excitement built hours before kick-off.
Many fans wore Neymar masks as part of a social media campaign titled #somostodosneymar ("We are all Neymar").
Brazil's players wore baseball caps bearing the slogan "Forca Neymar" (Go Neymar) as they got off the team bus at the Mineirao stadium.
Coach Luiz Felipe Scolari urged his team to use Neymar's injury as motivation in an eve-of-match rallying cry.
"We are playing for our country, it is everything we imagined and dreamed of, and also for Neymar."
Scolari opted to replace Neymar with 21-year-old Bernard. Bayern Munich's Dante came in for the suspended captain Luis Gustavo.
The Brazilians have committed more fouls than any other team in the tournament, and were accused of targeting Colombia's James Rodriguez in the last round.
Germany coach Joachim Loew urged semi-final referee, Mexico's Marco Rodriguez, to crack down on hard challenges to ensure Brazil do not go "beyond what is acceptable."
"It's the battle of two continents, Europe against south America. Brazil have 200 million fans, so we're playing the whole country, it's something unique," said Loew.
"I hope the referee Rodriguez will clamp down, because I have seen in the last few matches that Brazil's physical energy is going beyond of what we see in Europe.
"I have seen at this World Cup that the physical limits of what is acceptable have been surpassed."
Loew meanwhile is under no illusions about the hostile atmosphere his team is likely to experience.
"Brazil will unleash all it's passion and emotions into this match, it has been easy to see in the previous games," said the 54-year-old.
"In this stadium, any attack which comes near our goal will be accompanied by enormous shouts.
"We need to stay focused and not concentrate on the Brazilian players.
"The players will have to be courageous and it's essential that everyone does their job.
The winner of Tuesday's semi-final will advance to Sunday's final at Rio de Janeiro's Maracana Stadium where they will face either Argentina or the Netherlands, who play in Sao Paulo on Wednesday.
Off the pitch Tuesday, an English official from the FIFA partner company handling World Cup ticket packages was released by police a day after his arrest.
Ray Whelan, 64, had been held for questioning over an illegal ticket scalping ring.
Whelan's employers, Match Hospitality, insisted he was innocent.
"Match have complete faith that the facts will establish that he has not violated any laws," a statement said.
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