Afterwards, they strip naked in the locker room for impromptu victory celebrations.

Whether or not they confound the pundits and go on to lift the World Cup, co-hosts Japan have stamped their mark firmly on Asia's first World Cup -- and launched a craze for celebrations in the nude that has spread to growing numbers of their fans.

Communal bathing is a long-established tradition in Japan but the national team, who have made history by reaching the second round of the World Cup for the first time, have given it a spin of their own for the 21st century.

Prime Minister Junichiro Koizumi stumbled in on the team's celebrations after Sunday's 1-0 victory over Russia, although that reportedly did not prevent him giving a naked Junichi Inamoto, the goalscorer, a congratulatory hug.

"The Prime Minister came into the dressing room when we had our kit off," said Inamoto, who also scored in the team's 2-2 draw with Belgium. "Some of the lads were dancing around, though, I admit."

Japan have been at their World Cup base in Iwata since May 21.

ALL FOR ONE

Their French coach, Philippe Troussier, has been preaching the virtues of "collective effort" and an "all for one" approach during the tournament.

Japan finished top of their group after beating Tunisia 2-0 in Osaka on Friday, a far cry from their first appearance in the finals in 1998 when they lost all three games.

"Each game gets sweeter. The team just exploded after the (Tunisia) game," defender Tsuneyasu Miyamoto said.

"We all get naked and dance in the locker room," he added, when asked how the team celebrated after matches.

Japan, with an abundance of hot springs, has a tradition of nude communal bathing both in the natural springs and in single sex public bath houses in the towns and cities.

The bath house tradition had been on the decline in cities, if not in the rural areas.

But it is now showing signs of a revival in the suburbs with the emergence of a new type of bath house, blending tradition with such modern-day luxuries as jaccuzi sprays.

The Japan players spend much of their free time relaxing together in an outdoor hot spring bath at their hideaway in Shizuoka Prefecture, two hours south of Tokyo.

Defender Naoki Matsuda said the players often hold impromptu team talks in the bath.

Japanese fans, too, have taken to nudity in a big way as World Cup fever has swept the country.

Tens of thousands of people took to the streets of Osaka to party into the early hours of Saturday morning after the Tunisia game.

Hundreds of revellers stripped off to jump from bridges into the Dotomburi River.