Who will start in midfield for the All Blacks?

Once again the All Blacks have a tricky midfield puzzle to solve with the selectors having to decide whether to pick Anton Lienert-Brown, Seta Tamanivalu or Rieko Ioane to start against Australia this week.

The certainty is that Malakai Fekitoa is going to start, but the question is who will partner him? Fekitoa's versatility means that he can stay at centre and play with Lienert-Brown at second-five, or he can shift to No 12 and give Tamanivalu the No 13 jersey.

Lienert -Brown had a strong Super Rugby campaign with the Chiefs and looks well set up to play a direct and simple role of getting over the gainline and making his tackles.

Tamanivalu is a physical beast when he carries the ball, but looked a little daunted by the complexity of his defensive role when he won his two caps against Wales in June.

There is the option of introducing the 19-year-old Reiko Ioane at centre, but for all his obvious talents, it would be a surprise if they were willing to throw him into action so soon. He's played most of his Super Rugby this year on the wing and pushing him too early may not be the best path for his longer term development.

All Blacks head coach Steve Hansen has shown he's an astute judge of when and how to introduce younger, inexperienced players into test football.

Typically he's tended to work youngsters into the fray off the bench, building their exposure slowly. That's not always the way they choose to go and potentially, given Ioane has played at the Olympics, they may feel his ability to cope mentally is not necessarily reflective of someone who has only had a handful of Super Rugby games.

Assistant coach Ian Foster said there is a preferred plan in mind and that Tamanivalu's previous experience with the team through the June series, had perhaps given him a head start on the other two.

"It is early in the week and we are still finding a lot out," said Foster. "Seta has obviously been with us before so he is got a head start in terms of his knowledge of what we do. We saw a little bit of that today.

"But we thought Reiko learned well and what we saw at training was pretty positive and don't forget that Anton is still there and just learning it too.

"The expectation is there that they come up to speed pretty quick. They have to understand their roles and as we go through the week we will figure out who has learned the most the quickest. We have got a fairly good idea [about who will start]."

Ben Smith isn't being considered as a midfield starting option despite his proven ability to handle either role. He's again more likely to be designated injury cover.

While the situation isn't ideal in regards to the forthcoming test, having a number of young players come into the squad and experience life as an All Black has longer term benefits.

Ioane is just 19, Damian McKenzie 21 and Lienert-Brown 22. All three, especially Ioane and McKenzie, have masses of potential and the challenge for the coaches is to work out how to best pick and prepare the team for this weekend while also thinking about the future.

"It's getting that balance between seeing that potential at a young age and bringing them in here and just making sure we don't do too much too quick," says Foster.

"But at the same time we don't want to stifle the flair and the excitement that they have got too. There is an eye to the future clearly and even the likes of Seta is not old. Damian is young, Anton is young so there are some good possibilities for us."