Ian Foster backed captain Sam Cane but knows New Zealand are "under the spotlight" after they suffered a historic Rugby Championship defeat to Argentina on Saturday.

The Pumas moved to the top of the standings with their first away victory over the All Blacks, winning 25-18 in Christchurch.

While Michael Cheika's side were on cloud nine, the All Blacks crashed back down to earth after lifting the gloom with a win over South Africa at Ellis Park.

New Zealand head coach Foster was informed he would keep his job through to the Rugby World Cup in France next year following the win over the Springboks, but questions are being asked about his future again.

Cane has also come under fire and Foster hauled him off after he showed indiscipline to gift Argentina a penalty by tackling Pablo Matera without the ball 14 minutes from time, with Emiliano Boffelli punishing him by extending the lead to seven points.

Foster said: "Clearly he [Cane] is under the spotlight. We are all under the spotlight when things don't go well. But behind the scenes, [Cane is] strong.

"I thought a lot of his tackle and work around the breakdown was a big shift up in the last two games, and we are pleased with that.'"

Foster said he would be speaking to Cane about his hit on Matera.

He added: "Yeah, no doubt about that. We will work through all that. It's probably reflective of a team that's trying really, really hard and is close and not quite there."

There was good news for the All Blacks on Sunday, when Brodie Retallick was cleared to join the squad in Hamilton after recovering from a broken cheekbone.

Defeat for holders New Zealand was their fourth in six Tests this year and left them third in the table behind the Pumas and Australia.