'I'm not sure it's the way the game should go but it's definitely the way the game is going when you're under pressure.'

Rush defence will be grim reality in the biggest games at the Rugby World Cup, according to Springboks coach Rassie Erasmus, who predicts tries will be at a premium in Japan.

A trend of tense, low-scoring Tests continued in Wellington on Saturday when South Africa snared a dramatic 16-16 draw thanks to Hershcel Jantjies' converted try in the final minute.

The two heavyweight sides struggled to create scoring opportunities, bagging only one try apiece as smothering line speed shut down space and time.

It mirrored a series of defence-dominated contests in Europe last November when the leading World Cup contenders met.

Argentina have added rush defence to their armoury, resulting in stilted losses to New Zealand (20-16) and Australia (16-10) in the current Rugby Championship.

Erasmus said New Zealand's line speed has gone up a notch, further transforming major Tests into the forward-based contests of previous generations.

"I guess in the old days, the scores were 12-10, 15-12 and Test match rugby was like that ... it was only one or two tries normally," he said.

"I'm not sure it's the way the game should go but it's definitely the way the game is going when you're under pressure."

Erasmus said the way his team conjured a late score in such an intense contest was both valuable and satisfying eight weeks out from the World Cup in Japan.

While he felt his team were "lucky" after being dominated for much of the second half, he took lessons from the way they controlled most of the first spell ahead of a rematch with the All Blacks in their opening World Cup group game at Yokohama.

"We take a lot of positives out of this because they are the world No.1, they are the benchmark. We'll take a lot of belief out of this game."

Erasmus had only one apparent injury concern emerge ahead of their final Rugby Championship Test against Argentina in Salta on August 10.

Halfback Faf de Klerk failed a head knock assessment and didn't return, making way for match-winner Jantjies, who has bolted into the World Cup frame in the past week.

The 23-year-old bagged a double on debut in the win over Australia in Johannesburg and has injected an effervescence that Erasmus wants to bottle.

"Try-scoring looks like a really simple thing for him at this stage," he said.

"A guy like him you can keep the natural game flowing and you don't over-coach him too much with all the technical things."

- AAP