Christchurch - All Blacks stars Dan Carter and Sonny Bill Williams have been omitted from the squad named on Saturday for next weekend's Test against South Africa while injured wing Waisake Naholo is out of World Cup contention.
Coach Steve Hansen said that with the World Cup just two months away he had to "be brave" with selections for the Rugby Championship Test in Johannesburg.
"We're trying to juggle to pick the right team and then also give people an opportunity and rest some other people."
He said Carter and Williams both performed well in Friday night's 39-18 win over Argentina in Christchurch and if it was not a World Cup year then both would be on the flight to South Africa.
Without Carter, the world's leading point-scorer, Beauden Barrett, Colin Slade and uncapped Lima Sopoaga travel as the three fly-half options.
Ma'a Nonu is the only specialist inside centre with Ryan Crotty and Malakai Fekitoa also able to cover in Williams' absence.
"It's a balancing act, but at the same time we've got to be brave to find out some answers to some questions and what better place to find out some questions about people," Hansen said.
"It's a pressure situation against one of the best teams in the world and in their backyard on the high veldt so we'll get some good answers to some serious questions."
Naholo, an emerging star of New Zealand rugby who topped the try-scoring table in this year's Super 15 competition, had his World Cup hopes dashed when he broke a bone in his leg during his debut Test against Argentina.
"He'll be out for three months which means he's going to miss the World Cup which is pretty disappointing for him and for us," Hansen said.
Although Carter and Williams have been left out of the squad, and captain Richie McCaw's number seven understudy Sam Cane has not featured in the first three Tests of the year, Hansen said his World Cup squad of 31 was far from settled.
"No one's jumped ahead of anyone at the moment. We're just trying to find what is the best 31. We've got to get combinations, we've got to get versatility as well."
Lock James Broadhurst is the other uncapped player in the squad for South Africa, coming in for Jeremy Thrush, while Ben Smith, Conrad Smith and Aaron Smith appear for the first time since playing in the Super 15 final three weeks ago.
The All Blacks leave for South Africa on Saturday afternoon with a stopover in Sydney where Hansen said they would be able to watch television coverage of the Springboks Rugby Championship match against Australia in Brisbane.
New Zealand's 31-man squad:
Forwards: Dane Coles, Keven Mealamu, Codie Taylor, Wyatt Crockett, Ben Franks, Owen Franks, Nepo Laulala, Tony Woodcock, James Broadhurst, Brodie Retallick, Luke Romano, Samuel Whitelock, Jerome Kaino, Richie McCaw (captain), Liam Messam, Kieran Read, Victor Vito
Backs: Andy Ellis, TJ Perenara, Aaron Smith, Beauden Barrett, Colin Slade, Lima Sopoaga, Ryan Crotty, Malakai Fekitoa, Ma'a Nonu, Conrad Smith, Israel Dagg, Charles Piutau, Julian Savea, Ben Smith