Tokyo - Boxing All Black Sonny Bill Williams can have a David Beckham-like effect on Japanese rugby, says the International Rugby Board's (IRB) new chief executive Brett Gosper.
"The game needs big stars," Gosper said in his first formal interview in the job, comparing the celebrity status of Williams to that of former England soccer captain Beckham.
"It's great for the game to have stars who are larger than the game almost, that are larger than life," he told Reuters.
Williams, also New Zealand's heavyweight boxing champion, left the world champion All Blacks and Waikato Chiefs for a 12-match deal with Japan's Panasonic Wild Knights reportedly worth $100,000 per appearance.
"Sonny Bill Williams is one of two or three people in the world - a little bit like David Beckham - who can capture the imagination, hearts and minds of young kids, mums, dads, a cross-section of the population.
"That generates interest in the sport as well," added Gosper as cicadas chirped noisily outside an empty Chichibunomiya rugby stadium, headquarters of the Japan Rugby Football Union (JRFU)."
Williams, who helped New Zealand to retain the Bledisloe Cup last month, missed Japan's Top League season opener last Saturday but is expected make his debut this weekend in Sapporo.
Gosper, himself a former Australia under-21 international, rejected criticism that Williams's huge salary should have been invested in developing Japanese rugby at local level.
"It is a kind of indirect way of doing it," said the 53-year-old, managing director of the World Cup which will be held next in England in 2015 before Japan hosts Asia's first in 2019.
"Particularly in Japan, where there is a love for the celebrity factor, I think he's a terrific injection of interest in the game in Japan.
"I think it's a great way to spend the money that they've spent. It's now up to Japan to take advantage of that wonderful opportunity of having him here."
Despite Japan not having won a World Cup game in 21 years, Gosper said the future of the "Brave Blossoms" was in safe hands under Australian coach Eddie Jones.
"There's no question that a good-performing home team in their own World Cup is great for atmosphere, great for the home crowd and adds to the tournament," he said.
"We think that seven years out they have the time to gain the competition and be very competitive and step up a notch from where they were at the last World Cup.
"You want to see a step up in 2015 and then you've got the build-up to 2019. We think Japan will perform really well and we are confident 2019 will be a very special World Cup."
IRB chairman Bernard Lapasset agreed Japan had time to improve, saying they had tests away to Romania and Georgia in November as well as the visit of World Cup semi-finalists Wales next June.
"Seven years to change the game is totally possible," he said. "In the professional game seven years is a new generation, new players, new coaches.
"Eddie Jones is one of the most famous coaches in the world, with good experience and he is a strong leader. Eddie is a very clever guy with a good vision.
"He knows the players, knows the progress they have to deliver."