Cape Town – A victory for the Springbok warhorses on the side of the scrum … or the All Black whippets?

Which pair of notably contrasting flanks proves the more effective combination could have a key say in determining which way the massive World Cup Pool B opener goes at Yokohama (11:45 kick-off, SA time) on Saturday.

*** CLICK HERE TO SIGN UP FOR THE 'RUCKING WITH ROB HOUWING' NEWSLETTER ***

Naturally the gargantuan battle between the distinguished, highly-rated No 8s, Kieran Read and Duane Vermeulen – assessed in depth on Sport24 earlier this week – will be important too. They are hugely familiar foes to each other, whether in Tests or Super Rugby, and their “tale of the tape” is also almost identical.

But there’s an intriguing clash of styles in the flank scrap, where South Africa’s Siya Kolisi (captain, and open-sider) and Pieter-Steph du Toit (blindside) are pitted against a reasonably unorthodox-looking New Zealand duo: Sam Cane is there as their established, premier open-sider but the blindside spot is effectively occupied by another more tearaway-geared, fetcher-orientated character in Ardie Savea.

In other words, the All Blacks will not field a big-timber blindsider of the more customarily modern kind – often a player capable of doubling as a lock because of his generous physical dimensions, lineout-specialist qualities and brawn-laden style of play at close quarters.

Coincidentally, Australia will be going that route too, for their Pool D opener against Fiji earlier on Saturday, with renowned, low-centre-of-gravity pilfers David Pocock and Michael Hooper paired as the flanks and the only truly “big unit” in the loose trio being (Fijian-born) eighth-man Isi Naisarani.

In the recent past, Pocock has more customarily operated at No 8 when allied with Hooper in the same loose trio, so he brings an unconventional touch – standing only 1.83m – to the blindside jersey, despite his stockiness and broad shoulders.

But the All Blacks are following a similar template, prepared to look just a little “unbalanced” in several respects against the Boks when it comes to the makeup of their flank combo.

It is just another sign that head coach Steve Hansen hasn’t been fully enamoured with his more specialist blindside options since the retirement from international rugby after 81 caps at the end of 2017 of now French-based and 36-year-old Jerome Kaino.

Savea has a tough edge and the fevered, zealous energy of a Schalk Burger, but at 1.88m and 103kg he will surrender a fair bit in blindside physical proportions to South Africa’s in-form Du Toit, a former second-row staple figure who stands two metres and used to tip the scales around 120kg (he has consciously shed several of those kilos to cater for the mobility-related demands of his newer, highly successful stationing in the Bok No 7 shirt).

Given that Kolisi is also not the most classically-built of “moles” as South Africa’s opensider – he is taller than most Test customers there, at 1.89m – there is a discernible culture clash, if you like, in the flanker duels on Saturday.

If the match is contested on a heavy, wet pitch – there has been some talk of that transpiring, though the latest weather radar indicates improvement – then the more grunt-laden attributes offered by Du Toit and Kolisi could come in particularly handy for a tense, low-risk sort of “arm wrestle”.

But where Hansen will be hoping to cash in is Cane and Savea’s joint-effectiveness as stealers, considering their renowned ability to reach breakdowns quickly, and – Savea a special handful, by reputation – to act as effective linkers and extra prongs generally to attacking initiatives.

By restricting the meatier, more conventional blindsider Shannon Frizell of the Highlanders to the All Black bench (he had started the 16-16 draw in Wellington earlier this season) this weekend, the NZ brains trust do seem pretty interested in shifting the Boks around as much as possible.

Savea is unlikely to shirk the collisions and the broadly “dark art” facets of play against the Boks, but the Hurricanes flier would also love nothing more than to be an expressive, weaving and sprinting factor in loose, open play.

How well he merges the two responsibilities – and it is no simple ask – could be a defining aspect of the tussle; at least his direct rival Du Toit knows more precisely what his main chores will be on the red-letter occasion.

He will play to his treasured, no-frills strengths, making thumping tackles and driving the ball up with the sort of venom that usefully commits more than one defender, a lot of the time, to thwarting him.

Those qualities made him such a critical, stand-out presence in successive, valour-laden Bok results in Wellington’s Cake Tin between 2018 and 2019.

Savea has to be an “all sorts” factor in his uncustomary position … and despite his indisputable, game-breaking potential, that carries no written guarantees of success.

*Follow our chief writer on Twitter: @RobHouwing