The leading candidates to captain the All Blacks in Bledisloe Cup III

All Blacks head coach Ian Foster named his initial squad to travel to Australia for the Rugby Championship on Thursday, and there were some notable absentees.

Headlining the playing contingent who missed out on the trip to Perth for the first leg of their five-match tour on the other side of the Tasman are stand-in captain Sam Whitelock, veteran halfback Aaron Smith and star playmaker Richie Mo'unga.

All three players, who have stayed in New Zealand to attend the births of their respective babies and will miss next week's final Bledisloe Cup test against the Wallabies in Perth, are huge losses for the All Blacks.

Whitelock has flourished since taking over from the injured Sam Cane as All Blacks skipper, while Smith has deputised superbly as he notched up a ton of test matches against the Wallabies at Eden Park last week.

Mo'unga, too, has stamped his authority over the No 10 jersey, despite being pitted in a battle for starting honours with Beauden Barrett, but none of the trio will feature at Optus Stadium next Sunday.

The absence of Whitelock and Smith, in particular, raises questions about who will take the helm of the All Blacks as captain.

Without those two, or Cane, the All Blacks have just one player, Barrett, with captaincy experience at international level.

Barrett was handed captaincy duties against the Barbarians at Twickenham four years ago, but hasn't been called on to lead the All Blacks since then.

After playing second-fiddle to Mo'unga for most of this season, it seemed unlikely that the 30-year-old would be asked to lead the side again in 2021, but prospect could become a reality in Western Australia.

Not only has the absence of Whitelock and Smith paved the way for a new skipper to come to the fore, Mo'unga's no-show means Barrett has a clear run to the No 10 jersey for the Perth test.

Those two factors could combine to see the two-time World Rugby Player of the Year lead the All Blacks for the second time in his career, but he isn't the only candidate in the running to fill in for Whitelock and Smith.

Speculation has mounted that both Ardie Savea and Codie Taylor could captain the All Blacks for the first time in their respective careers, while experienced lock Brodie Retallick looms as another potential contender.

Similarly to Barrett's situation at No 10, the non-selection of Aaron Smith could see TJ Perenara come into the starting team for the Bledisloe Cup encounter, and with 70 tests to his name, he too could come into the captaincy reckoning.

Perenara's rival to start at halfback, Brad Weber, is one of five further players - Scott Barrett, Patrick Tuipulotu, Rieko Ioane and Dalton Papalii - with captaincy experience at Super Rugby level in the current All Blacks squad.

Despite the number of leadership options at his disposal, Foster remained tight-lipped about who he will hand the captaincy to for next week's test.

"To be honest, we're pretty clear but I wanted the last couple of days, as we got certainty of the squad and who was coming and all the family situations, we decided to leave our leaders to have a couple of days grace and just to enjoy being at home," Foster said.

"They've done a fantastic job behind the scenes getting the squad ready to go and we've got plenty of time now with the Sunday test match. When we get over there, we've got three or four days to really acclimatise, get used to contact.

"Part of that process tomorrow is going to be to sit down with our leadership group and just sort through the structure we're going to operate in in the short-term. We'll let you guys know as soon as we can."

Cane, the full-time All Blacks captain who was ruled out with a long-term pectoral injury in March, revealed on Instagram earlier this month that he should be ready to return to the field within the next two months.

Foster had initially planned to bring the 29-year-old back into the thick of things via the NPC, but with New Zealand in the midst of a nationwide lockdown, the country's premier provincial competition has gone on hold indefinitely.

That, and the quarantine restrictions between New Zealand and Australia, has thrown a spanner in Cane's comeback plans, but Foster said a decision about his skipper's return to play will be made a few weeks before he takes to the field.

"His time-frame is still that but the ideal thing is if we were playing in New Zealand, we could have brought him back through NPC and the Steamers," Foster said.

"Now, with the uncertainty of when the NPC is going to start and with quarantining into Queensland, we'll have to make those decisions.

"Unfortunately, we can't really crystal ball-gaze at everything and so we'll probably make those decisions in two or three weeks."