Ahead of their first training session in Tokyo tomorrow, the problems are mounting for the Japanese Super Rugby outfit who have adopted Singapore as their second home.

The Sunwolves will have just one warm-up match against a local selection before their Feb 27 debut against the Johannesburg-based Lions in Tokyo.

Having assembled their 34-man squad only last month - with just 15 players who have Test experience - the team are already two months behind their rivals in pre-season preparations.

Their cause is not helped by key Japanese national players like captain Michael Leitch, full-back Ayumu Goromaru and scrum-half Fumiaki Tanaka signing for other clubs.

On Friday, utility back Kotaro Matsushima became the seventh Japanese player to join an overseas Super Rugby outfit, moving to the Melbourne Rebels.

It is believed that the draw of more lucrative contracts and the Sunwolves' back-room instability were behind the transfers.

Speaking to the Japanese media last week, Sunwolves coach Mark Hammett - who was appointed in December - admitted that his side could be undermanned and overwhelmed in their first season.

"There's no doubt we are behind the eight-ball and there might be some harsh lessons on the field," said the former All Blacks hooker and Hurricanes head coach.

"Super Rugby is probably the hardest competition in the world. That's why it's important that we play our style of rugby and be innovative in the way we attack."

The sport's equivalent of Champions League football, Super Rugby features six South African clubs, five each from New Zealand and Australia, and two new expansion teams from Japan and Argentina.

Calling themselves the Jaguares, the Argentinians have recruited the majority of their national team and could spring a surprise or two.

The Sunwolves, on the other hand, must tackle a gruelling schedule, with home matches split between Tokyo and Singapore and away ties in South Africa and Australia.

The squad will be away from Tokyo for 83 days out of 140 and 15 of their flights will be longer than seven hours in duration, including a three-week road trip in South Africa.

They will make their Singapore bow on March 12 against South Africa's Cheetahs before clashes against three-time champions Bulls (March 26) and Stormers (May 14) at the National Stadium.

In the Sunwolves squad are Samoa fly-half Tusi Pisi, former Auckland Blues lock Liaki Moli and lock Hitoshi Ono, Japan's most-capped player with 96 international appearances.

Without their own training base as yet, the Sunwolves will use the facilities of Japanese clubs in the coming months, as their players look to familiarise themselves with one another.

"There are some players here we've never met before," fly-half Harumichi Tatekawa said when the team assembled in Tokyo for physical tests this week.

"Obviously, communication will be key to creating a strong team."

Last year's Super Rugby tournament was won by the Highlanders of New Zealand, led by All Blacks stars Aaron Smith and Ben Smith.

Grouped geographically, the top team in each of the four conferences will qualify for the quarter-finals. The next three-best teams in the Australasian group and the second-placed team in the South African section will progress as wild cards.

While a quarter-final spot looks too big an ask for the Sunwolves, the hope is for them to build on Japan's good showing at the recent Rugby World Cup, headlined by a stunning pool-stage win over South Africa.

Hammett said: "Rugby is on the rise in Japan. We're hoping the Sunwolves can keep improving Japanese rugby.

"Everyone is excited but a little bit nervous."

•Tickets for the Sunwolves' matches at the National Stadium can be purchased at www.sportshubtix.sg