Fly-half Handre Pollard kicked 19 points as South Africa beat Argentina 29-10 in Gqeberha on Saturday to take a four-point lead over New Zealand in The Rugby Championship.
Pollard, 27, slotted five first-half penalties for a 15-3 half-time lead and converted tries by winger Makazole Mapimpi and hooker Malcolm Marx.
Flanker Pablo Matera scored a post-hooter try for the Pumas, which fly-half Nicolas Sanchez converted after coming off the bench in the second half for Domingo Miotti, who kicked a penalty.
The 19-point victory for the Rugby World Cup winners was almost identical to last weekend when they defeated the Pumas by 20 points in the opening round.
But while the previous win also yielded a bonus point for scoring three tries, the Springboks failed second time round as they scored only two.
"Argentina are very passionate. We stuck to our game plan but they defended well, we made mistakes and they contested well in the lineouts," Springboks captain and flanker Siya Kolisi said.
"I'm very happy with the win. Obviously we wanted the bonus point but good luck to them as they defended well and got the last try," he added.
Argentina had forwards Rodrigo Bruni and Tomas Lavanini yellow carded and, in the first half alone, conceded 13 penalties.
"Our discipline was very, very bad. Too many penalties, they kept scoring points, points, points," Pumas skipper Julian Montoya said.
"We must decide what we did wrong and keep on working. We finished with a try but we did not do what we wanted to. We played too much in our half," the hooker added.
Both matches were staged in the eastern Cape city formerly called Port Elizabeth because of the coronavirus situation in the South American nation.
Australia were scheduled to host New Zealand next weekend in the other second round fixture, but the All Blacks pulled out on Friday amid uncertainty around Covid-19 travel restrictions.
South Africa and Argentina planned to share a chartered jet to Australia on Sunday, but that has been put on hold pending a revised decision by the organisers, SANZAAR, on match venues and dates.
The future of this season's southern hemisphere competition became uncertain when New Zealand unilaterally decided to withdraw from the fixture in Perth.
Wallabies coach Dave Rennie was "bloody angry" at the move and Rugby Australia chief Andy Marinos claimed he learnt about it only through the media.
- Tournament Europe-bound? -
Amid uncertainty triggered by the pandemic, options include staging double-headers in other Australian venues, South Africa or Europe.
There has been speculation that Cardiff, Dublin, London and Paris could host matches -- a commercially attractive proposition with the likelihood of huge crowds.
There is a precedent for playing in Europe with Argentina 'hosting' Australia in London in 2016 while, five years earlier, the Crusaders and Sharks played a Super Rugby match in the English capital.
While South Africa successfully hosted an eight-match tour by the British and Irish Lions, which ended this month, crowds have been barred from sport events since early 2019 due to Covid-19.
South Africa's deputy health minister Joe Phaahla admitted this week a third wave of the pandemic was remaining "stubbornly in our midst" in the African country most affected with 78,983 deaths.
Civil unrest in the republic last month, triggered by the jailing of former president Jacob Zuma for shunning a graft inquiry, claimed 342 lives and could count against South Africa becoming hosts.