The game kicked off at 6 p.m. local time after German President Horst Koehler declared the monthlong tournament open during a ceremony.
Win or lose, Germans are counting on the world's largest sporting event -- watched by hundreds of millions around the globe -- as a chance to show off the "new Germany": reunified, rejuvenated and prospering.
Germans are realistic about their team's chances against the 31 other top soccer teams in the world, with many saying Germany should be happy to make it to the quarterfinals.
Yet others hold fast to dreams of a repeat of the 1954 "Miracle from Bern" when the underdog West German team beat Hungary for the World Cup title in Switzerland, catapulting the fledgling nation out of the shadows of its World War II history and boosting self-confidence at home.
With the shadow of the Nazis ever present, Germans have long tended to steer away from overt displays of patriotism. But more than 15 years after the former East and West Germanys fused and 60 years since the war, such taboos seem to be melting away.
In Munich, the streets were packed with fans bedecked in every possible incarnation of the black, red and gold German national colors, including painted faces, caps, beaded rings, leis, and people who simply wrapped themselves in the nation's flag.
Scores of people also wore plastic replicas of German spiked World War I helmets painted either with the national colors or as soccer balls.
Germany stands to benefit from the million fans pouring into the country to attend the matches in 12 cities. Fans are expected to pack not only the stadiums, but hundreds of organized outdoor viewing points, as well as the nation's many beer gardens, pubs and restaurants.
Police aren't taking any chances. A spike in racially motivated attacks in Berlin and surrounding areas ahead of the tournament raised concerns about neo-Nazis. An African group in the capital had even planned to issue a list of "no-go areas" for dark-skinned fans, but decided against it after meetings with police helped allay their concerns.
British and Polish hooligans have also raised fears -- hundreds of known troublemakers from England had their passports confiscated and officials tightened Germany's border with Poland -- an hour's train ride from Berlin.
There was a visible police presence in Munich, with groups of officers stationed at regular intervals throughout the city and no sign of any hooliganism. Police said 2,800 were on hand.
In a special pre-Cup service in Munich's famous Frauenkirche cathedral -- where German-born Pope Benedict XVI once presided as Cardinal Joseph Ratzinger -- Cardinal Friedrich Wetter prayed with hundreds of fans for a "festival of peace and friendship."
"Only a few can play on the field, but we can all participate with our hope and joy," he told the worshippers, from an altar behind a giant white soccer ball.
The World Cup opens with indicators of business and consumer optimism running high and the German economy -- Europe's biggest -- picking up after several stagnant years. Economists say the tournament may contribute 0.2 percentage points of the 1.8 percent growth this year. A million foreign visitors are expected to spend a billion euros.
In her inaugural weekly video podcast, Chancellor Angela Merkel urged a "top-class performance" on and off the field.
The excitement of the World Cup spread beyond Germany.
In Denmark, which did not qualify, all newspapers featured the World Cup on their front pages, while public radio throughout the day played sound bites from sports commentators yelling and shouting when Danish teams scored in past tournaments.
"Football's popularity reaches all corners of the world," Former Polish soccer star Zbigniew Boniek wrote in Fakt newspaper. "One can of course also talk about hooligans making trouble, which applies to a tiny percentage of real fans, but actually football today unites the whole world."
A potential cloud over the tournament is the political dispute surrounding qualifier Iran, whose President Mahmoud Ahmadinejad has indicated he may travel to Germany to support the national team in person. No specific plans have been announced. Vice President Mohammed Aliabadi came to Germany and is expected to attend.
Ahmadinejad has called the Holocaust a "myth" and said the Jewish state should be "wiped off the map," leading a German Jewish group and Amnesty International to organize demonstrations before the team's first game in Nuremberg on Sunday.
German far-right activists are threatening to demonstrate in support of the Iranian president.