Cape Town - Michael Hooper and David Pocock.
They are reasons alone for the Springboks to have to think very carefully over how they shape their loose trio - and more - for Saturday’s Rugby Championship showdown with Australia in Brisbane (12:00 SA time).
For all the Wallabies’ own issues results-wise in recent times, that dynamic, low-centre-of-gravity pair are almost always part of their first-team furniture these days and consistently deadly as poachers on the deck.
That is demonstrated by their impressive combined tally of international caps: 155.
Hooper seems especially well set to end his career with an extraordinary tally, fitness and other factors permitting, as his 84 have come even before he turns 27 (Zimbabwean-born brave-heart Pocock is a more advanced 30).
Coach Michael Cheika has traditionally been extremely willing to field them together, even if you are effectively putting out two open-side flank specialists.
Pocock has adapted comfortably to the cares of No 8 duty, a role he has more regularly fulfilled for the Wallabies since late 2015 or thereabouts.
Despite their successive, heavy reverses in the tournament so far to the All Blacks - 38-13 in Sydney, 40-12 in Auckland - it will be surprise if Cheika breaks up the scavenging alliance against the Boks.
He has been balancing out the loose trio by fielding the immense physical specimen who is 21-year-old Lukhan Tui (123kg) as the blindside flank.
The Reds man doubles as a lock forward, and if he plays again on the side of the scrum at Suncorp Stadium he is one reason why Rassie Erasmus, the Bok coach, may well be tempted to fight fire with physical fire by recalling his own, versatile Pieter-Steph du Toit (2m, 120kg) to the No 7 jersey.
That would automatically mean the SA skipper, Siya Kolisi, reverting to open-side responsibility, despite the very split views among critics about which flanker berth actually suits the Stormers-based player best.
A long-time personal view is that Kolisi, hardly the most classically pile-driving No 7, should be persevered with in more of a “fetching” capacity, even if not a natural mole in build terms.
But if that is what happens on Saturday (and roaming Warren Whiteley is retained as eighth-man rather than asking Francois Louw to re-adapt to that jersey) then the role of hooker Malcolm Marx comes into sharp focus.
There have been suggestions in sections of the SA media this week that Erasmus may crack the whip with personnel who under-achieved against Argentina and Mendoza - and that one of the shock sacrifices in such a scenario might even be No 2 muscle-man Marx.
It would have been unthinkable a few weeks back to even contemplate omitting Marx from the starting line-up for the first time in his Test career - 14 starts since starting his Bok career with two appearances off the bench - when fit.
And would it be sacrilegious anyway?
It is hugely tempting to take that view.
While there are some ongoing question marks around his lineout throwing, the 24-year-old Lions player is a juggernaut in driving and mauling play; he is near unstoppable as a ball-carrier within a couple of metres of the try-line.
But we cannot overlook something else, and no less critical: like a small, select bunch of co-hookers around the world, he is also probably the Springboks’ most conspicuous presence as a ball-stealer on the ground, actually eclipsing any loose forward colleague a lot of the time in that capacity.
Yes, there is a case for “shaking up” Marx a little by preferring his admirable deputy, Bongi Mbonambi, this weekend – Mbonambi had been excellent in the England series triumph during June.
But in a game Erasmus admits is a “must win” after the events in Mendoza, leaving out one of the few genuine jewels, by reputation, in the Springbok crown somehow seems foolhardy.
Put it this way: no Marx on Saturday, and Messrs Pocock and Hooper would be licking their lips for the breakdown contest even more than they usually do before a Test match …
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