Despite Japan's superb performances at the recent Rugby World Cup in England, Sanzar are still "nervous" about the participation of their franchise, the Sunwolves, in 2016's Super Rugby tournament.
That was the word from New Zealand Rugby chief executive Steve Tew who admitted that there was uncertainty about the Sunwolves joining Super Rugby which caused some uneasiness among the southern hemisphere collective.
"We're all very excited by what the Japanese achieved at Rugby World Cup but we remain pretty nervous about their readiness for Super Rugby, and that's their next step forward," he told Fairfax Media.
"I wouldn't say it's shaky, but we are concerned about any expansion when you bring new teams into a competition, and it takes a bit of time for them to bed down.
"We had a Sanzar meeting in Sydney this week and a Japanese guy gave a very detailed presentation on things in place.
"A lot of that was encouraging, but they haven't announced a coach yet and haven't got a full player roster, so they're two things they've got to put the foot on the throttle for."
Tew said there was plenty of positivity about Argentina's new side who will also be making their Super Rugby bow.
"Argentina will be in very, very good shape," he added.
"They're very well organised, very prepared and they've got a very strong player roster. They might actually be a quite considerable [threat] and they're going to add considerable colour to the competition."