It's no secret that in New Zealand, they are spoiled for choice when it comes to rugby.

Number one in league, number one in union, and about two full teams worth of world-class talent means the biggest problem the Kiwis face is choosing between their Uzi or their AK-47.

Nevertheless, one problem the All Blacks have been facing as of late is finding a suitable centre combination to run with for the foreseeable future.

Despite numerous options, injury, form and general incompatibility means that inside and outside centre are two positions that head coach Steve Hansen has not yet 100% nailed down yet.

Current incumbents Ryan Crotty and Malakai Fekitoa have both been put on notice by Hansen, who stated that midfield spots for The Rugby Championship would be “hotly contested”, and that the gaps were not all filled yet.

Let's break down the pros and cons of all the realistic candidates come the mid-year tests.

The incumbents

Ryan Crotty

Solid but unspectacular option at both 12 and 13. Possesses a solid skillset, and never looks out of place in a New Zealand jersey, but is poised to be a second choice safety option for life, rather than a first choice starter. Unlikely to start given the bulk of options for The Rugby Championship.

Malakai Fekitoa

For the longest time, Malakai Fekitoa has drawn comparisons to the great Ma'a Nonu, who just vacated one centre position post the World Cup. Fekitoa immediately slipped into Nonu's jersey, and although his game has not taken off this year as predicted to, it's likely he will maintain his spot, at least for the remainder of the year. Shortcomings in defence make him a risk at outside, but more plentiful options at inside make him more valuable there also.

The challengers

George Moala

Although he has played most of his Super Rugby at inside centre, he played outside in his 1 appearance in New Zealand's most recent test series against Wales. A strong runner and good offloader, Moala is perhaps the least talented man on this list (which is not saying a whole lot), but has not failed anyone in his 2 test caps to date. May not cut it against South Africa or Australia but if his ability to play wing also means he may get a look in there.

Charlie Ngatai

Charlie Ngatai looked almost certain to add to his 1 cap in the June test this year, but most unfortunately missed out on the squad due to concussion. A strong runner, fast sprinter and lethal offloader, Ngatai can fit in at both centre positions, a fact alone that makes him very hard to leave out of the squad. Is perhaps in the best Super Rugby form of all the men listed here.

Seta Tamanivalu

Seta Tamanivalu made three appearances for his nation off the bench against Wales, and was reasonable impressive with the game time he was given. A great prospect for the future, it would be rather surprising seeing him left out of the All Blacks' squad come TRC, and given how the All Blacks operate, he may even get a start against Argentina if form warrants.

Sonny Bill Williams

Realistically, calling Sonny Bill Williams a “challenger” is incorrect. So important to the side is he that Steve Hansen has confirmed that he will be rushed back from the Rio de Janeiro Olympic Games and straight into the New Zealand squad with less than nine days until their first game against Australia in The Rugby Championship. Expect him to start immediately ahead of Ryan Crotty, or as reasonably quickly as possible as he readjusts to the 15s game.

The wildcards

Beauden Barrett

As unlikely as it is, this journalist would love to see Beauden Barrett deployed as an inside center for New Zealand, if for nothing else but to see the combination between himself and Aaron Cruden. His blinding speed and great playmaking skills would, I believe, make him one of the more devastating centre prospects in the world, but it would take a match day injury crisis to see this in effect.

Rieko Ioane

Despite only a handful of caps for the Auckland Blues, the Ioane brothers announced themselves to the rugby world on the sevens scene, where their devastating running and incredible combination of power and speed made them irresistible in the open field. Steve Hansen has publicly named both brothers as potential All Blacks bolters, meaning centre/winger Rieko could potentially get a look in.