Tokyo (AFP) - Treble-chasing New Zealand's supremacy looks set to face a serious test from multiple challengers as the clock ticks down to an eagerly awaited Rugby World Cup in Japan.
The hosts will kick off the tournament on Friday as favourites against minnows Russia -- a mark of their progress after years spent as the World Cup's whipping boys.
But the serious business starts on Saturday, with the All Blacks in a blockbuster clash with South Africa that could be a precursor of the final on November 2.
France play Argentina, top-ranked Ireland face Scotland and Eddie Jones's England are against Tonga on a bumper opening weekend for the first Rugby World Cup held in Asia.
Organisers hope to ignite rugby passions in Japan and the region at large, saying the World Cup is on course to sell out and that Friday's opener will set a tournament record for viewing figures in a single country.
Japan's Brave Blossoms have set themselves the goal of reaching the knock-out phase for the first time, aiming to climb out of a tight Pool A also including Ireland, Scotland and Samoa.
"The players are keen to get out there," said Japan's assistant coach Tony Brown. "We have an experienced group and those guys have got the team under control -- they understand what they have to do."
New Zealand ended a 24-year drought when they nervily won their second World Cup on home soil in 2011, and dominated in 2015 as coach Steve Hansen crafted a remarkable run of success.
But questions have been raised over the mighty All Blacks after a rocky patch of form which saw them lose their long-term grip on rugby's world number-one ranking.
South Africa, on the rise under coach Rassie Erasmus, will hope to strike an early blow while England, Ireland and Six Nations champions Wales also look capable of winning the Webb Ellis Cup.
- 'Spectacular hosts' -
England have assembled a formidable array of ball-carriers under the canny Jones, the ex-Japan coach who led the Brave Blossoms to their stunning win over South Africa in 2015.
The 2003 champions slumped to an embarrassing pool-stage exit in 2015 but they will be expecting to top Pool C where they are bracketed with France, Argentina, USA and Tonga.
However, Wales's hopes were dealt a blow when long-standing attack coach Rob Howley was sent home over a suspected breach of rules against betting, badly disrupting their preparations.
In a tournament rich in sub-plots, Gatland is one of a number of coaches stepping down after the World Cup, along with New Zealand's Steve Hansen, Ireland's Joe Schmidt and Jacques Brunel of France.
The French have endured a lean period but they have a fine record at the World Cup, reaching 1987, 1999 and 2011 finals, and there are positive signs since Fabien Galthie bolstered Brunel's backroom staff.
Australia also shape up as potential dark horses after they shook off a turbulent period -- marked by poor results and the controversial sacking of fullback Israel Folau for homophobia -- to hand New Zealand a record defeat in Perth.
Organisers hope the six-week, 48-game tournament will spark rugby interest in Japan -- where baseball, football and sumo enjoy far greater popularity -- and elsewhere in Asia.
Despite limited knowledge of the game, great enthusiasm has already been on show with 15,000 fans packing out a Wales training session in Kitakyushu and Japanese children treating the All Blacks to a haka.
"You only need to visit the host cities or turn on TV or social media to see that this tournament is going to be very, very big and popular," said World Rugby CEO Brett Gosper.
"Towns and cities are embracing the teams with huge passion. Japan is already proving to be a spectacular host -- it's an eye-opener."