All Blacks ready to face Springboks

The All Blacks will hope for a fast start against South Africa in their Rugby Championship opener on Sunday (NZ time) to defuse the threat of their "bomb squad" replacements.

Rassie Erasmus's Springboks used their bench players to great effect in winning the Rugby World Cup in 2019, bringing on powerful forwards in the second half to grind teams down with physical intensity.

His successor Jacques Nienaber has stuck with the tactic, keeping a 6-2 split of forwards and backs on the bench for the clash at Mbombela Stadium, a few weeks after his team crushed Wales 30-14 with a dominant last quarter in the series decider.

The All Blacks, meanwhile, are coming off a 2-1 home series loss to Ireland, having been slow out of the blocks in the last two defeats in Dunedin and Wellington.

"I think they've used that pretty well in the past two or three years, their impact," All Blacks lock Scott Barrett told reporters of the 'Bomb Squad'.

"Particularly they target big moments in the second half around the set piece and try to get back into the game or close out a game using what they perceive as strengths and they are strengths of their game.

"So our bench is aware of that, as well as our starters - that it's good to start well and keep right on them."

Indiscipline cost the All Blacks in the Ireland series, with prop Angus Ta'avao given a red card for a high tackle in Dunedin and two other players drawing yellow.

The Rugby Championship will continue a 20-minute red card trial introduced last year, which will allow teams to replace dismissed players after 20 minutes rather than play a man down for the rest of the match.

The 1.97m Barrett, who has had his own troubles getting low enough in the past, said tackling had been a focus at training during the week.

"It's a technical thing around the tackle that .... we get our height right particularly against a low ball-carrying team and a physical team," said Barrett.

"We're working on our habits and making sure we get that right."