Two second-half penalties from MornÃ© Steyn saw South Africa come from behind to win 22-17 in a brutal match against Argentina.
The Springboks were unable to produce the same clinical finishing that saw them rack up so many point last weekend, sucked into a breakdown battle that they often lost until Steyn's boot prevailed in the closing stages.
Argentina, as widely expected, were completely unrecognisable from the sham that turned up at Soccer City last weekend and conceded nine tries.
A repeat of last weekend's 73-13 hammering in Soweto was always unlikely, with Argentina far more productive at containing the Springboks at the breakdown and in the set-pieces.
The hosts general attitude though was outstanding, taking the game to a South Africa side whose execution was far from the excellent level produced the week before.
Mendoza was the setting for the 18-18 draw between these two sides last season and once more South Africa looked unsettled early on.
The hosts couldn't have wished for a better start. Capitalising on loose ball at the ruck, Argentina surged upfield and from an attacking lineout five metres out they unleashed a clever rolling maul, with Juan Manuel Leguizamon touching down despite a hint of obstruction inside the opening three minutes.
Steyn and Felipe Contepomi traded penalties before the Springboks drew level, Bjorn Basson finding his way over after a harried turnover at the ruck created an overlap on the left-hand side.
It was a score that perhaps would have eluded a maturing South Africa side a year ago, but the 2013 version is a different beast and made the most of this rare chance.
JuandrÃ© Kruger's try was ruled out for an earlier knock-on at the lineout closely after Ruan Pienaar was also denied a score, beaten to the bounce in the dead-ball area by Martin Landajo.
South Africa were struggling to find the fluidity that served them so well a week before and their attitude was puzzling; a poor decision to opt for the corner instead of a simple penalty backfired on the Boks as an easy three points went begging with 25 minutes gone.
Their attack was also littered with knock-ons, with every single one giving the home side and their supporters renewed hope.
That hope was then converted into a second try; centre Marcelo Bosch forcing his way over through the tackle of Jannie du Plessis to put the Pumas up 17-10, Steyn responding with a long-range penalty before half-time.
Fired up by a rollicking from Heyneke Meyer, the Springboks were reinvigorated after the break and another Steyn penalty cut the deficit to just one point.
The penalty count began to creep up on the Pumas as the second half wore on, who showed at times too much enthusiasm at the breakdown.
Contepomi's departure with a shoulder injury felt like hammerblow to Argentina's prospects, but the continued tenacity shown by the hosts at the ruck meant that they kept their slender lead.
Repetitive small errors didn't help to calm what was already a tempestuous atmosphere and young lock Eben Etzebeth was penalised for lashing out, due to his unhappiness over a reported bite from an Argentinian player.
Experience was introduced in the form of Bismarck du Plessis, who won his 50th cap off the bench and capped it with a series of effective choke tackles to stifle Argentina's possession - but the Boks were still facing an uphill battle.
Steyn's penalty in the 71st minute after a collapsed maul finally put South Africa ahead for the first time in the match - a slender two-point lead silencing the crowd as the match drew to a close.
Desperate to create a final opportunity, Argentina failed to produce the necessary field position to generate a penalty or drop goal, instead finding themselves pinned back in their own 22.
Steyn's final penalty confirmed the result, but Argentina should take heart from an encouraging performance, despite their first win in The Rugby Championship still eluding them against an average South African performance.
Tries: Leguizamon, Bosch
Cons: Contepomi 2
For South Africa:
Pens: Steyn 5
Argentina: 15 Lucas Gonzalez Amorosino, 14 Gonzalo Camacho, 13 Marcelo Bosch, 12 Felipe Contepomi (captain), 11 Horacio Agulla, 10 NicolÃ¡s SÃ¡nchez, 9 MartÃn Landajo, 8 Leonardo Senatore, 7 Juan Manuel LeguizamÃ³n, 6 Pablo Matera, 5 Mariano Galarza, 4 Julio FarÃas Cabello, 3 Juan Figallo, 2 Eusebio GuiÃ±azÃº,1 Marcos Ayerza.
Replacements: 16 AgustÃn Creevy, 17 Nahuel Lobo, 18 Tomas Lavaninni, 19 Benjamin Macome, 20 TomÃ¡s Cubelli, 21 Santiago FernÃ¡ndez, 22 Joaquin Tuculet.
South Africa: 15 Willie le Roux, 14 Bjorn Basson, 13 JJ Engelbrecht, 12 Jean de Villiers (c), 11 Bryan Habana, 10 MornÃ© Steyn, 9 Ruan Pienaar, 8 Duane Vermeulen, 7 Willem Alberts, 6 Francois Louw, 5 JuandrÃ© Kruger, 4 Eben Etzebeth, 3 Jannie du Plessis, 2 Adriaan Strauss, 1 Tendai Mtawarira.
Replacements: 16 Bismarck du Plessis, 17 GurthrÃ¶ Steenkamp, 18 Coenie Oosthuizen, 19 Flip Van Der Merwe, 20 Siya Kolisi, 21 Jano Vermaak, 22 Pat Lambie, 23 Jan Serfontein.
Date: Saturday, August 24
Venue: Estadio Malvinas Argentinas, Mendoza
Kick-off: 16.10 (19.10 GMT)
Referee: Steve Walsh (Australia)
Assistant referees:John Lacey (Ireland), Pascal GauzÃ¨re (France)
TMO: Marshall Kilgore (Ireland)
by Ben Coles