Rugby Championship: All Blacks great Mils Muliaina hits out at NZ Rugby treatment of coach Ian Foster

All Blacks centurion Mils Muliaina has hit out at NZ Rugby's treatment of head coach Ian Foster, after guiding his team to a stunning form reversal against South Africa at Johannesburg.

Riding a three-game losing streak, with just one win over his previous six games, Foster's future at the helm looked bleak, before New Zealand turned their fortunes around with a 35-23 win over the world champions at their Ellis Park fortress.

But while the performance has won over many of Foster's critics, NZ Rugby chief executive Mark Robinson has refused to confirm the incumbent will still be in charge, when the All Blacks next face Argentina on August 27.

"We've been having conversations right through this time," said Robinson. "We believe we know where we stand, we've just got to work through that with him."

That's not good enough, Muliaina told Newshub.

"[Foster] was asked last night if he thought he was going to be the coach and Mark Robinson has come out again, and we're still unclear about that," he said. "It's been a bit like that for Ian Foster - it just seems he's walking on eggshells.

"There was a review after the end-of-year tour, another review after the Irish tests and here we are again two weeks later, another review.

"I've never heard of so many reviews in my life, but given the performance they had last night, it's clear that Ian Foster is making headway.

"I'd like to see him stay until the end of the championship, before they have another review. I don't understand why they need another review every second game."

Ian Foster has the support of senior All Blacks players
Ian Foster has the support of senior All Blacks players. Photo credit: Getty Images

Muliaina insists Foster has every reason to feel upbeat over the showing, but Robinson's refusal to endorse the coach has put a dampener on the mood.

"There is uncertainty once again, when really they should have been celebrating a tremendous performance from the All Blacks after a hard couple of weeks," he said.

"There's still a bit of unknown over what's going on, and it's watered down what Ian Foster and his men produced last night."

Foster is expected to front media later on Sunday.