Ian Foster explains thinking behind halfback switch

At this stage of the Rugby Championship, it's hard to determine whether Ian Foster and the All Blacks selectors are taking a 'horses for courses' approach, or simply spreading the load.

Foster has made six changes to the starting line-up for tonight's match against the Pumas, with two of those 'forced' by injury.

Argentina have traditionally been a side that the All Blacks have been happy to experiment against, with 14 players making their debuts against the Pumas between 2012 and 2019. Foster has resisted making sweeping changes this year, however, or handing any of his charges test debuts.

That's likely dictated in part by the shock Argentina gave New Zealand last year, when they scored a first-ever win over the men in black. The All Blacks are also still bedding in new combinations - particularly in the loose forwards and midfield.

That means Foster has retained the growing combination of David Havili and Anton Lienert-Brown in the centres, while a head-knock suffered by Ardie Savea last week has seen Luke Jacobson take his spot at No 8, joining Akira Ioane and Dalton Papalii.

Argentina perhaps pose a more physical threat than Australia, so Jacobson's addition might be tailor-made for the match - but there's one other change that appears to be partly based on the opposition, and partly based on the need to spread the workload.

The abrasive TJ Perenara will start at halfback in place of Brad Weber in this evening's match - a move Foster indicated was very much planned in advance.

"For the first two weeks, we'd always anticipated switching them around," Foster said on Friday.

Foster also confirmed that while the selectors did want to spread the load around, Perenara's more physical game perhaps suited playing against Argentina compared with Weber's fast-paced style.

"It's probably a loading issue but also, [last week] I think I said that [it was a] great opportunity to reward Brad for some really good work and we were delighted with his game. I thought it was a very, very fast game, it suited him, and he did what he did really well.

"So he should be pretty satisfied with his performance and now it's TJ's turn. I know it's a different opposition but he's training really well and loved his impact off the bench last week and I'm sure he'll give us the same as a starter."

The two men are vying to entrench themselves as the semi-permanent back-up to Aaron Smith, who has remained in New Zealand for at least the early stages of the All Blacks' end of year tour. Weber perhaps offers a more similar play style to Smith, while Perenara brings with him a point of difference.

Whomever Foster favours, both men will get multiple runs over the coming month, with Foster not expecting any players to play all the Rugby Championship matches in Australia - with one asterisk.

"I don't anticipate someone playing five in a row," he said. "But with the combinations and the ramifications of injuries and travel and quarantining, I certainly wouldn't bet against it."

Tonight's match kicks off at 5:05pm AEST from the Gold Coast.