"We are concerned about any expansion when you bring new teams into a competition and it takes a bit of time for it to bed down," NZ Rugby boss Steve Tew said.
"We are nervous about the strength the Kings will bring to that competition too."
Sanzar had explained why they had gone for the new structure and the rationale behind taking a little bit of a gamble on bringing Japan and Argentina into the competition.
"We are all very excited by what Japan achieved at Rugby World Cup but we remain pretty nervous about their readiness for Investec Super Rugby and that is their next step forward," said Tew.
"On the upside it looks like the Argentinian side will be in very, very good shape. Very well organized, very prepared and got a very strong playing roster and they might actually be a considerable worry. They will add some significant amount of colour to the competition."
Sanzar was still working hard with the Japanese to help them with their franchise. Their representative addressed a Sanzar meeting in Sydney this week about details they had in place.
"They have not announced a coach yet so that is clearly an issue and they have not got a playing roster completely full so they are the two issues they have to put their foot on the throttle for."
McCaw now considering options
Closer to home, Tew had spoken regularly to All Black captain Richie McCaw since the squad returned from their World Cup triumph. He wanted to enjoy playing this year without any distractions about his future but was now consolidating his plans.
"He has just asked for a little bit more time before he finally makes a decision and an announcement.
"He won't be too far away from getting to that point and I think if we give him a little bit more space and have a little bit more patience we will all be rewarded with the ultimate answer shortly."
