JUST PUT YOURSELF in one of the New Zealand forwards’ boots for a second.

You’ve just made a miserable start to the second half against South Africa, whose clever lineout play has yielded their third try and a 21-0 lead.

You’ve already lost one of your starting pack, Scott Barrett, to a red card in the first half and you sense that there’s scope for things to get worse. You glance over at the touchline and maybe you spot only one or two of them at first.

There’s world-class replacement hooker Bongi Mbonambi applying grip spray to his arms as he gets set to enter the fray. And there’s powerful sub tighthead Trevor Nyakane flicking his legs in anticipation. Oh, there’s the offload-addicted lock RG Snyman glowering at you.

But who’s that? Dynamic back row Kwagga Smith is checking his strapping one last time as the jackal-hunting flanker Marco van Staden takes a deep breath to steady his adrenaline. Another second row, Jean Kleyn, looks utterly determined to add to his growing reputation among Springboks fans.

And there he is, the seventh Boks forward among their replacements, the cake-loving, tackle-breaking loosehead prop Ox Nché.

They have to wait a couple of minutes more as Canan Moodie’s try is disallowed but then they’re all on at once. After 46 minutes of the game, the Springboks send on all seven fresh forwards, who join the outstanding Pieter-Steph du Toit to form a new pack.

Just a minute later, there’s a scrum. Oh dear. This fresh Boks group send you backpedalling in dominant fashion, with centre Jordie Barrett standing in as the extra Kiwi forward and getting a close-up example of what South Africans can do.

Ardie Savea somehow manages to pop the ball off the base of your retreating scrum but it’s a deeply dispiriting moment. Another 33 minutes of this?

A minute later, scrum time again. This one is a South African scrum penalty, continuing the theme that had been so firmly implanted by the Boks’ starting pack.

Du Toit’s yellow card then briefly takes the sting out of the bench impact but even without him, they’re soon marching you over your own tryline for a maul try finished by Mbonambi.

The pain keeps coming. Smith wins a breakdown turnover. Snyman breaks through your tiring defence. Nché’s startling linespeed forces another handling error from your attack. Your scrum gets pulverised yet again. The Boks kick into the corner for another five-metre chance. As you anticipate another heavy maul, a variation. Du Toit pops off the top and Smith smashes through to score.

There’s a consolation try before it’s over but the final whistle comes as a relief. The onslaught is finally over.

Under Rassie Erasmus and Jacques Nienaber, the Springboks have made a 6/2 split of forwards and backs on their bench a genuine calling card. Their famous, feared ‘Bomb Squad’ of impact forwards played a huge role in the 2019 World Cup success. Rather than being upset about not starting games, the Bomb Squad ended up getting tattoos to mark their contribution.

Well, now we’ve seen a 7/1 bench split from the South Africans.

They had initially gone 6/2 for last Friday night’s against New Zealand but soon before kick-off announced a change to their matchday 23. Replacement Willie le Roux, who plays at fullback, had pulled out. But it wasn’t another back coming into the number 23 shirt. Instead, back row Smith was introduced.

The Boks didn’t have to go this way. They had other backs with them in London and could have stuck with 6/2. Evidently, Erasmus and Nienaber have been plotting this new development and the timing felt right. 

The results were patently successful and it now remains to be seen if South Africa repeat the trick at the World Cup. It would be a surprise if they don’t.

The strategy comes with obvious risks. Lightning-quick scrum-half Cobus Reinach was the only back on their bench against New Zealand, but he covers the wing. Indeed, that’s where Reinach came on with 17 minutes left, replacing Makazole Mapimpi on the left wing.

As we see below, the mischievous Erasmus looked delighted to be able to trial it.

Still, even one early backline injury could force a little bit of chaos with a 7/1 bench.

And two backline injuries would have meant one of the South African forwards shifting into the backs. Smith could probably do a job at inside centre but it would obviously be far from ideal, particularly if it happened early in a game.

Even the 6/2 bench split brings a clear element of risk, as Toulouse’s defeat to Leinster in the Champions Cup last season underlined. That day, an early injury to centre Pierre-Louis Barassi meant rejigging the backline. Toulouse shifted scrum-half Antoine Dupont to out-half, while out-half Romain Ntamack moved to centre. It was deeply prohibitive to their chances of winning.

So the Springboks will have to proceed with caution if the 7/1 is going to become their new thing. The first sighting last weekend was rather frightening. Ireland, who play South Africa in their third pool game in the World Cup, would have watched on with interest and surely some trepidation.

The starting Boks pack unleashed everything they had into the first half, knowing that they’d be off early in the second. Steven Kitshoff, Malcolm Marx, Frans Malherbe, Eben Etzebeth, Franco Mostert, Siya Kolisi, and Duane Vermeulen going all-out is about as menacing as it gets and the All Blacks couldn’t live with them.

The Springboks' starting pack watch on after being replaced.

The Boks, whose coaching staff includes the deeply analytical Felix Jones, are nothing if not studious, so we have to presume they’ve got the numbers on how often they or other teams lose two backs to injury. They’ll almost certainly have calculated how much risk is actually involved.

If they’re going to drive on with the 7/1, they’ll also be planning for worst-case scenarios. So it would be no surprise Smith and others have been learning the roles involved in playing in midfield, something they probably did anyway with 6/2.

The Boks have four scrum-halves in their World Cup squad and it now seems even more obvious that they will need to show flexibility.

Faf de Klerk and Jaden Hendrikse could certainly move to out-half, while Reinach and Grant Williams are capable of playing on the wing.

The sight of the seven Boks forwards readying themselves to come on at Twickenham was almost comical but it was no laughing matter for the All Blacks.

Back in the old days, replacements in rugby were meant only to cover injuries. It was a 15-player game. Indeed, some within the sport argue for a reduction in the number of replacements allowed to ensure more fatigue, and therefore more attacking chances and slightly less physicality, within matches.

But that’s not the case right now and the Boks are absolutely entitled to pick as many forwards on the bench as they like. It comes with the risk of being left with a muddled, mixed-up team but the advantage was there for all to see in London.

Erasmus loves when the Boks get other teams thinking. He loves it even more when the Boks get others worrying. He’s achieved that yet again.