Alternative All Blacks role mooted for 21-year-old Tupou Vaa'i

There's perhaps just one certain starter in the forward pack when the All Blacks assemble to play the Wallabies on August 7, and that's captain Sam Whitelock.

Who partners the Crusader in the second row is very much up for debate, however, with Ian Foster sticking with five locks for the upcoming Bledisloe Cup series and Rugby Championship.

Scott Barrett, Patrick Tuipulotu and Brodie Retallick were all given opportunities to showcase their talents in the Pasifika series but, at least from the outside looking in, none of that trio unequivocally locked down a starting position for next month.

That's certainly the take from Super Rugby centurions James Parsons and Bryn Hall, who acknowledged that all three players have advantages to their game.

Speaking on the latest episode of the Aotearoa Rugby Pod, Hall suggested that Barrett and Retallick might have the inside running over Tuipulotu on account of their strong combinations with the All Blacks captain.

Retallick, in particular, is a man that could again scale the heights of 2017 when he was named World Rugby Player of the Year - but he'll need some more time in the saddle after recently returning from two seasons in Japan.

"Brodie Retallick, before he left to Japan, was the best lock - and arguably the best player - in the world," Hall asserted. "The more that he's going to be able to get himself engrained back in the environment, playing test footy at that kind of level, he's definitely a guy that you've got to have in the conversation to work with Sam.

"You've obviously got Scott Barrett and Sam Whitelock, who work together as well. So that's an advantage you do have with that Crusaders combo."

Parsons suspects that the All Blacks will employ a 'horses for courses' approach, given the unparalleled depth the team currently possesses in the second row.

"I don't think you can go wrong with any match-up, to be honest," he said.

"Brodie Retallick, he just doesn't need many games to come back into his own. I thought he looked another 20 to 25 per cent better [from] Dunedin to Hamilton. He was impressive off the bench and he started looking like the Brodie that we're accustomed to - destroying rucks, destroying guys in the tackle. He's only going to get better the more opportunities he gets.

"We can't forget the growth that Patty has made and the work that Scott Barrett has done over the years."

That still leaves one man out of the equation, however - 21-year-old Tupou Vaa'i.

After bearing a heavy workload for the Chiefs throughout the Super Rugby season, Vaa'i was unused by the All Blacks throughout July - though a slight Achilles niggle also hampered the youngster's chances of selection.

With four experienced locks ahead of him in the queue, Vaa'i might struggle to fight his way into the matchday 23, let alone the starting side.

Parsons, however, had a slightly left-field suggestion that might pay dividends.

"He's quite different to the other four," the former All Blacks hooker said.

"He's more in a lock/six mould. He could potentially fit that bench role, especially against the Wallabies, quite nicely."

The All Blacks have employed Scott Barrett at blindside flanker on a small handful of occasions in the past - most recently, the infamous loss to England in the 2019 Rugby World Cup semi-finals.

While Vaa'i has the physicality to potentially step into that kind of role, the All Blacks aren't exactly short of options in the back row either.

Akira Ioane and Shannon Frizell both started matches in the No 6 jersey in July while Ethan Blackadder has primarily played on the blindside flank for the Crusaders. Luke Jacobson, until this year, was also looming as a potential long-term No 6 for the All Blacks while Dalton Papalii has earned ample caps for the Blues with the 6 on his back.

Whether Vaa'i is employed in the second row or on the flank, he'll have a hard task ahead of him if he wants to usurp the players currently higher up in the queue.