Tupou entered the fray in the 47th minute with the Australian scrum floundering and a 18-17 deficit to boot.
When the final siren rung out in front of 27,849 at Suncorp Stadium he had forced a penalty that provided three critical points on a platter, crashed over the gain line with every carry and stiffened the Australian scrum right up.
He was the difference in the second half and must start against Argentina this time next week as before he was called upon the Wallabies looked a rather unconvincing outfit.
There was no abhorrent part of their game which hindered the quest to kill the four game losing streak but by the same token, no part of their game was particularly convincing.
Outside of the red zone the Australian attack was a spluttering, messy affair but that was somewhat to be expected with Kurtley Beale and Matt Toomua forming a fresh 10-12 pairing.
The Tupou-less scrum crumbled after making a rapid recovery in the second Bledisloe while the lineout was reasonable considering Adam Coleman’s late withdrawal.
The defence was similarly solid without setting the world on fire, with the Wallabies able to repel a handful of South African raids in the red zone.
All those facets of the Australian game fell short of a pass mark but it was a 7-3 penalty count through the first 40 that hurt their cause, leaving them pinned in their own half for the majority of the first term.
When they did hold onto the ball and kick to corners with poise, the attack fired.
That was exactly how Michael Hooper put his name on the scoresheet in the 2nd minute, a sublime Beale offload putting Lukhan Tui in space before five pick and drives finished in five points for the Australian skipper.
The Springboks, in contrast, were accumulating their points through a typical South African grind.
Their first try came off the back of a dominant rolling maul as Bongi Mbonambi fell over the line in the 15th minute.
The second was the result of a smart Faf De Klerk kick, a botched Rory Arnold-Will Genia lineout transfer and subsequent shoddy defence.
Makazole Mapimpi the beneficiary of a pinpoint De Klerk pass that put him over in the right corner.
Elton Jantjies kept the visitors’ score ticking over but a booming 54-metre Reece Hodge penalty after the final siren leaving the score poised at 18-17 in the visitors’ favour at the break.
The first 15 minutes of the second term was simply bizarre.
Both teams traded jabs in each other’s 22 but neither could land any sort of significant blow in the form of a five-pointer.
Toomua put the Wallabies back in front with a simple shot at goal from 25 out when Hooper finally decided it was time to play it safe and opt for the lead instead of shooting a try, it proved to be a masterstroke.
The Boks chased the game with some overcooked kicks, passes and dodgy hands quelling any momentum they managed to build.
A pair of crooked – according to Glen Jackson – Folau Faingaa throws then killed the Australian attack as they turned the tables on the South Africans but Tupou stamped himself on the match by folding Tendai Mtawarira and Toomua took full advantage by adding another three points.
The Australian lead was out to five but this match was far from over.
With just under two-and-a-half minutes to play a scrappy set in the Australian 22 almost resulted in a Francois Louw try but the TMO ruled Malcolm Marx knocked the ball on in the lead up to set up another scrum five out from the Wallabies’ line.
The final siren rang out with the Boks, once again, feeding a scrum five out from the Australian line.
But Bernard Foley plucked an intercept as the South Africans threatened to break the dam and Genia booted the ball into touch, a wave of relieved fans erupting as the pill sailed into the stands.
Tries: Hooper, Toomua
Cons: Toomua 2
Pens: Toomua 2, Hodge
Tries: Mbonambi, Mapimpi
Pens: Jantjies 2