It is, in fact, the most contestable part of the team. They have, probably, six genuine candidates pushing for places and all of them have strong claims to be involved.
The six in contention are Sonny Bill Williams, Ryan Crotty, Anton Lienert-Brown, Malakai Fekitoa, George Moala and Rieko Ioane. And complicating the picture is that three of them are equally as comfortable at second-five as they are at centre.
At the moment it doesn't appear to be a straightforward choice for the selectors. None of the individuals in questions are battering the door down with their form: most of them have been playing solidly without having ignited and in the case of Williams, he's only managed one full game since returning from a nasty Achilles injury.
In a perfect world all six of them will go up another gear in the next five or six weeks and prove that they are in form and ready to be let loose. Then it will be a case of the selectors having to determine the best combination.
That's when the fun will really begin. What exactly would be New Zealand's best centre pairing if everyone was in form?
And maybe there is more than one answer to that depending on what the coaches feel will work best in their overall strategy.
The probability is high that Williams is their preferred starting No 12 to play the Lions. He's been out of rugby for an age but has returned in typically immaculate condition.
What he's short of is game time to hone his skills and instincts. There's plenty of time, though, for him to find his rhythm and balance his game between direct running and neat offloading.
Everyone knows his talents and the threat he poses when he's confident. If he gets somewhere close to the form he was in at the World Cup, he'll start.
That would be a little tough on Crotty who established himself in the All Blacks No 12 jersey last year. He was one of the surprise packages - becoming more composed and effective the more he played.
But if Williams starts, Crotty could easily partner him at centre. His level-head, accuracy and secure defence is a big attraction and the selectors may well be reluctant to take on the Lions without Crotty heavily involved.
The alternate partnership most likely to be given heavy consideration is staring with Crotty and pairing him with Lienert-Brown. Those two developed a good understanding in the five tests they played together last year and Lienert-Brown individually shone.
He's in possession of a vast range of skills and has the temperament to play at the highest level. If those two start, it opens the option to use Williams off the bench from where he's been able to make a big impact in the past.
None of this means the door is shut on the others. Fekitoa had some good tests last year after a slow start. If he can up his involvement and impact in the coming weeks, he'll be looked at because he's shown himself capable of big things in big tests.
Moala delivered a huge performance against Wales last year and may have enjoyed an extended run on the back of it but for injury. His running game has caught the eye at times this year but his distribution and awareness remains a weakness.
The wild card is Ioane who has pace, size and power and immense natural talent. Probably the only thing counting against him is his ability to play effectively on the wing where the All Blacks are currently a little short of resources given the injuries to Israel Dagg and Nehe Milner-Skudder.
