New Zealand head coach Dave Rennie said on Monday that playing a four-test series against South Africa "will be a lot tougher than a Rugby World Cup".
Finalists in the four-yearly World Cup have to play seven matches, but the strength of opponents varies considerably.
"But facing the Springboks will be great. Both sides will be about a year out from the (2027) World Cup when this series finishes so we will certainly learn a lot," said Rennie.
South Africa edged New Zealand 12-11 in the 2023 World Cup final in Paris, and they could face each other at the quarterfinals stage of the global showpiece in Australia next year.
Rennie told reporters in Johannesburg, where the first test will be staged on Saturday, that the All Blacks had benefited from three warm-up victories against South African franchises.
Some pundits have expressed doubts regarding the value of the matches given their opponents lacked stars on Springbok duty and had just started pre-season training.
The Stormers faded in the closing stages to lose 38-21 to the All Blacks, who then scored 54 points against the Sharks and 50 against the Bulls.
"We used a lot of players – all bar three of the touring party have played – which has been good for us," said the head coach.
"There have been some genuinely high quality performances from individuals and that has put a lot of (selection) pressure on us.
"When we name our side for the first test we are going to leave out some really good players. Over four tests, we could use up to 30 players."
Rennie, who replaced Scott Robertson last March, said New Zealand could win the series "if we play at our best and force the Springboks to play below their best".
The coach expects the reigning world champions to play to their strengths at Ellis Park as they seek to stretch a 12-test winning streak.
"They will see the scrum as a strength. I think what they have been good at is applying pressure from set pieces.
"They force back-to-back penalties and put you in a corner. Then, they are the best in the world at turning that pressure into points.
"Our discipline will be really important, our accuracy will be really important, and our set pieces will be massive."
The second test is set for Cape Town on August 29, the third for Soccer City stadium in Johannesburg on September 5 and the last for American city Baltimore on September 12.