Tighthead props might not command widespread sex appeal but, in a rugby context, they are among the most important and highly-paid players in the world game.

Few observers are completely au fait with the dark arts of the exclusive front-row club. Everyone knows, however, that without a strong and stable set piece you might as well not turn up.

For five years, All Black success in this regard has been achieved in large part due to their world-class tightheads; the Owen Franks-Charlie Faumuina one-two punch.

Since 2010, Franks has owned the No3 jersey in 94 tests, with Faumuina offering significant impact through deceptive footwork and ball carrying skills off the bench in 38 of his 50 tests.

All that is about to change. Faumuina has departed for France, and with Franks battling injury, he is likely to be spelled during the Rugby Championship in the interests of ensuring the 29-year-old's longevity.

Franks has been in typically destructive form despite an Achilles tendon causing him major issues this season. He hobbled off at times for the Crusaders - to the point it threatened his availability for the Super Rugby final. With a view through to the 2019 World Cup, it will now be on the All Blacks to get Franks right.

"He has played a lot of rugby and at some point we're going to have to address his Achilles problems because they are causing him issues," All Blacks coach Steve Hansen said. "The only thing that is going to do that is giving him time out of the game.

"We'll have to assess when that is going to be when he comes back in and make some decisions. He's a vital cog in our team, particularly after losing Charlie. We wouldn't want to lose him for too long a period. We've got plans in place for addressing his long-term career but they're not for public consumption just yet."

Faumuina's immediate exit opens the door for another tighthead, and Chiefs prop Nepo Laulala has the inside running. Laulala played four tests in 2015 but then missed all of last season after a knee reconstruction. He is the natural successor, ahead of Chiefs teammate Atu Moli, who is injured, and the Hurricanes' Jeffery Toomaga-Allen. All three attended the All Blacks' two-day wider-training camp in Christchurch this week, working closely with guru Mike Cron.

Elsewhere the All Blacks are expected to take a steady-as-she-goes approach with their 33-man Rugby Championship squad. The end of year tour, when four more players will be taken north, presents more scope for emerging talent.

The only contentious area comes in the crowded outside backs, where Julian Savea could be squeezed out.

Nehe Milner-Skudder missed the Lions series because he lacked game-time. With that now under his belt, and his zip back, he will be hard to leave out.

The thing about Milner-Skudder is his fast feet and playmaking abilities offer the All Blacks a point of difference. Of the outside backs used during the Lions series, it was clear Savea did not fire - and with him left out of the Hurricanes starting side for their semifinal in Johannesburg, with Wes Goosen preferred, patience must be running out at national level. It could be that Savea is given time to rediscover his love for the game with Wellington in the provincial season.

Omitting Savea, the 54-test veteran, would allow the All Blacks to include Israel Dagg, Waisake Naholo, Jordie Barrett and Ben Smith alongside Milner-Skudder, with Damian McKenzie floating in a utility capacity. McKenzie could also cover first five-eighth behind Beauden Barrett and Lima Sopoaga following Aaron Cruden's departure to France.

Incumbents at lock, hooker, midfield, halfback and loose forward should all be retained.

Charlie Ngatai probably needs more time to return to peak form after significant time out with concussions, while Crusaders centre Jack Goodhue may also have to wait a little longer for his test debut.