Argentina ran out of gas after leading 14-10 at half-time as they suffered a 23rd loss in 29 Tests since the 2015 World Cup, going down 34-21 to the South Africans in Durban.
South Africa scored a bonus-point 34-21 Rugby Championship first round victory over Argentina with six tries compensating for woeful goal-kicking by Handre Pollard.
Wingers Aphiwe Dyantyi and Makazole Mapimpi bagged two each in Durban as the Springboks dominated the second half having trailed by nine points earlier.
Experienced fly-half Pollard missed five of seven shots at goal, which could have proven costly against stronger opposition than the Pumas.
New Argentina coach Mario Ledesma watched his team run out of gas after leading 14-10 at half-time as they suffered a 23rd loss in 29 Tests since the 2015 World Cup.
But the South Americans impressed sufficiently in patches to suggest they could be tougher opponents when the teams clash again next Saturday in Mendoza.
South African coach Rassie Erasmus said his team were far from where they needed to be and rated only 25 minutes of the game as "satisfactory".
South Africa lie second on points difference behind title-holders New Zealand, who beat Australia 38-13 in Sydney earlier Saturday.
Winning captain and loose forward Siya Kolisi said: "We did not start the way we wanted to today.
"Discipline was a problem. It is something that we have been working on for the past five weeks.
"We cannot give away penalties and expect to win games, but our effort pulled us through.
"As much as we are making mistakes, we are getting better and better, but are not close to where we want to be.
Argentina hooker and skipper Agustin Creevy said: "I think the lineouts and the scrums were not good for us. We lost a lot of ball.
"I think it was a really tough game -- every game is really tough for us. South Africa have really strong guys and we could not stop them. We need to work on that."
The home side established a foothold in Argentine territory from the kick-off and constant pressure paid off on eight minutes when centre Lukhanyo Am scored his first Test try.
Am used his strength to hold off two Pumas and dot down at a far-from-full 52,000-seat Kings Park stadium after Faf de Klerk set him up.
Nicolas Sanchez created and scored the first Argentine try on 15 minutes when his up-and-under kick was not cleared and he regained possession to go over between the posts.
A Sanchez conversion gave the South Americans a two-point lead they stretched to nine when the fly-half also added the extra points to a Pablo Matera try.
When Kolisi was dispossessed near the halfway line, the visitors moved the ball quickly down the left wing and Matera scored.
South Africa, who had plenty of ball and spent a lot of time inside the Argentine half, got back into the match on 32 minutes through a touch of magic from Willie le Roux.
A perfectly weighted cross kick from the veteran full-back found Dyantyi who powered over, but Pollard once more failed to convert.
Pollard was having an off-day with his goal-kicking and also fluffed a penalty attempt just before the break, leaving Argentina with a 14-10 half-time advantage.
The tide turned dramatically in the second half with tries from Dyantyi and Mapimpi (two) lifting South Africa to a 27-14 lead despite Pollard struggling from the kicking tee.
A Matias Moroni try converted by Sanchez cut the gap to six points before De Klerk scored and Pollard converted from in front of the posts to complete the scoring.