Rugby Championship: All Blacks coach Ian Foster must keep job after victory over South Africa, insists veteran sportscaster Brendon Telfer

Veteran sportscaster Brendon Telfer insists NZ Rugby has missed its chance to sack All Blacks coach Ian Foster and must now retain him, after the bounceback win over South Africa last weekend.

Foster's future with the team remains uncertain, despite guiding them to a 35-23 victory at the Springboks' Ellis Park stronghold to end a three-match losing slump and a stretch of just one win in six games.

New Zealand lost a series to Ireland for the first time last month and barely fired a shot at Mbombela in their South African opener.

The embattled head coach was expected to lose his job after the two-game series against the world champions, but the nature of the Johannesburg result and the strong public support of senior players has put his employers in a difficult situation.

"I think it would be very unwise for the rugby union to fire him now," Telfer told AM. "If they were going to get rid of him, they should have done it and the end of the Irish series.

"What the All Blacks did on Sunday morning I don't think has been fully appreciated in this country. This was one of the best-ever performances by an All Blacks side in South Africa.

"We've been going to South Africa for 92 years... we've had seven test series in South Africa and only ever won one. For Ian Foster to come back from South Africa with a 1-1 result from a two-match test series put him at or near the very top of All Blacks coachs that have taken teams to South Africa."

NZ Rugby chief executive Mark Robinson has been widely criticised for failing to endorse - or otherwise - Foster after the performance, taking the gloss off a result that very few outside the All Blacks camp saw coming.

"The rugby union have handled this very poorly," said Telfer. "If they're going to get rid of him - and they do have the right, if they're not happy with his work - they can't do it at the moment.

"They have to wait at least until this Rugby Championship is finished in about six weeks. You can't fire an All Blacks coach after a performance like that in South Africa, sorry."

Foster and his All Blacks have returned to New Zealand, and are due to re-assemble later this week for their next assignment against Argentina at Christchurch on August 27.