Energized by Senegal's stunning opening upset of champion France, World Cup fans poured into Japan for day two of the world's biggest sports showdown Saturday as authorities ratcheted up security.

The tournament's focus moved to Japan Saturday with a 1-1 tie between Ireland and African underdog Cameroon following Friday's opening ceremony in South Korea. The two countries are co-hosting the first World Cup to be held in Asia.

"It's getting really exciting," said Naohiro Tsukamoto, manager at the World Sports Cafe in Tokyo. "With all this Western culture coming in, soccer fans and non-soccer fans alike are going to get into the World Cup."

Like South Korea, where Senegal stunned the world by upsetting France 1-0 on Friday, Japan was beefing up security to prevent terrorist strikes or soccer riots.

Soccer fans, meanwhile, seemed ready for something wild — an anything-goes tournament in which underdogs have a shot at felling the giants.

"There is enough precedent for a whirlwind," Japan's Sankei Shimbun newspaper forecast in its front-page coverage of the opening night upset. "Japan-Korea World Cup dream opening," blared the banner headline of the mass circulation Asahi Shimbun.

"As a result of last night's game, you've already got the defending champions with their backs to the wall," said Keith Cooper, spokesman for soccer's governing body, FIFA. "I don't think there's any reason to think the group matches will be tedious — precisely the opposite, I expect."

Germany blanked Saudi Arabia 8-0 in Japan. Meanwhile, in South Korea, Uruguay was playing Denmark in Ulson.

The United States plays its first match Wednesday against Portugal in Suwon, South Korea.

The first World Cup in Asia, and the first to be divided between two countries, opened Friday in Seoul with fireworks, traditional dance, and bristling security.

More than 11,500 soldiers and police officers were mobilized to secure the venue — at least one security worker per six spectators and more than enough to form a human ring around the 64,640-seat stadium.

Military helicopters hovered close by during the opening ceremony and the match, and air force jets were on standby to defend a no-fly zone the South Korean government has imposed on all 10 of its World Cup venues.

Organizers in Japan, which also has 10 venues and will play host to half of the 64 matches, have likewise marshaled thousands of police.

In the Tokyo suburb of Saitama, site of England's opening match against Sweden on Sunday, local officials have rallied citizen watch groups to patrol streets and report riotous activity.

The provincial government has set aside a separate stadium for ticketless fans to view the World Cup free of charge on a big-screen television — and hopefully spare local shops a potentially raucous onslaught.

A total of 22 Britons have been refused entry to Japan under a government clampdown on suspected hooligans, a British Embassy official said Saturday.

An estimated 3,500 of an expected 8,000 British fans were already in Tokyo, many making their way downtown where England fans set up a welcoming tent Saturday in a vacant lot in a trendy nightclub district. Kevin Miles, an organizer of the "Fan Embassy," said restaurants seemed eager for the extra customers.

But Masao Arai, owner of a pub near the stadium in Saitama, said he will close as soon as the referee sounds the final whistle, for fear of damage to his windows.

Before the game, he will not begrudge thirsty foreign fans a cold beer — but no refills, please. "They can get one glass," Arai said. "After that, they're free to go."