Siya Kolisi-led world champions South Africa are poised to replace New Zealand as Rugby Championship leaders on Saturday by defeating Argentina for a second time in eight days.
The All Blacks top the Springboks on points difference after both secured bonus-point victories last weekend in the opening round of the annual southern hemisphere competition.
However, next weekend's scheduled match between Australia and New Zealand in Perth has been called off after the All Blacks announced Friday that they were withdrawing from the tournament until fixtures have been rescheduled to work around coronavirus restrictions.
New Zealand Rugby said the three-time world champions would remain at home while the tournament's governing body SANZAAR finalises plans for its remaining matches, including the 100th Test between the All Blacks and the Springboks which is due to be played in Dunedin on September 25.
"We remain 100 percent committed to playing in the entire Rugby Championship in 2021 and are working closely with SANZAAR to look at a range of options to reschedule these important matches," said NZR chief executive Mark Robinson.
The lockdown in New Zealand and their decision to suspend All Blacks fixtures will offer South Africa a chance to secure a bonus-point victory and take a five-point lead in the standings.
New Zealand scored eight tries to hammer Australia 57-22 in Auckland last weekend before Elton Jantjies kicked 17 points as South Africa ground out a 32-12 victory over Argentina.
The contrast in styles of the winning teams was stark with the All Blacks playing at a much faster tempo than fellow three-time world champions the Springboks.
"While we were pleased with the victory and starting our Rugby Championship campaign on a winning note, there is a lot of room for improvement," admits South Africa head coach Jacques Nienaber.
"We have identified a few areas we need to work on if we want to defend our title successfully, and we worked on those aspects of our game at training this week.
"Argentina will come hard at us, so we know we need to perform much better than last weekend to get the desired result.
"The Pumas play with a lot of passion, much like we do, so they will want to show their fighting spirit, which will set the scene for another challenging match between us."
- Changed team -
Nienaber and counterpart Mario Ledesma have rung the changes for a match that will be played behind closed doors because of coronavirus in eastern Cape city Gqeberha (formerly Port Elizabeth).
The Springboks have made 11 alterations, including recalling backline stars like wingers Cheslin Kolbe and Makazole Mapimpi and fly-half Handre Pollard, who were rested last weekend.
Among the forwards, lock Marvin Orie starts for the first time after five appearances off the bench, which allows Eben Etzebeth to take a break.
It will be a special Test for the other Springbok lock, Lood de Jager, as he joins Pollard, prop Steven Kitshoff and centre Damian de Allende in reaching the 50-cap milestone this season.
World Cup-winning captain Kolisi is a bundle of energy as he is the only Springbok to start all five Tests this season against Georgia, the British and Irish Lions (three) and Argentina.
"We want to remain the number one ranked team in the world so we must keep winning," was the message from the flanker to his teammates this week.
Ledesma has made six personnel and two positional changes as the Pumas seek a second victory in South Africa, where they have lost 13 Tests.
The biggest surprise is the demotion of long-serving fly-half Nicolas Sanchez to the bench with Domingo Miotti taking his place.
Sanchez has contributed 40 of the 89 points scored by Argentina in four Tests this year against Romania, Wales (two) and South Africa.
But the Stade Francais playmaker is among the eight replacements, and highly likely to be introduced at some stage of the match.