Flanker Siya Kolisi will make his first appearance for South Africa this season in a Rugby World Cup warm-up against Argentina Saturday, but not in his usual role of captain.
Coach Rassie Erasmus said Kolisi, who is recovering from a knee injury, may be substituted during the first half in Pretoria and chose veteran hooker Schalk Brits as skipper.
Number eight Duane Vermeulen (twice) and lock Eben Etzebeth (once) captained the Springboks during the Rugby Championship campaign in which they beat Australia and Argentina and drew with New Zealand.
At 38 years and three months, Brits will become the second oldest captain of the Springboks after retired lock Victor Matfield, who had the honour when 38 years and 172 days.
"I have asked Siya to empty his tank and go hard for as long as he can," Erasmus said after making 15 changes to the side that triumphed 46-13 in Argentina last Saturday to win the Rugby Championship.
"I told him he might even come off in the first half as he has played less than 50 minutes of Currie Cup rugby in the last 12 weeks.
"But I need him to have a taste of Test rugby again before we leave for Japan," referring to the absence of Kolisi from the team since a loss in Wales last November.
While Kolisi is guaranteed a place in the 31-man World Cup squad to be named on Monday August 26, many of those who will face the Pumas at Loftus Versfeld are fighting for seats on the flight to Tokyo.
"Some of these players will know they are on the plane but for others it is make or break -- and even if they do not make the plane there will be six standby roles to be identified," said Erasmus.
"I am really excited to see what they can do on Saturday, to prove their own cases, and also show just how strong South African rugby is."
In the backline, full-back Warrick Gelant, centre Andre Esterhuizen and winger Dillyn Leyds, are marginal cases for inclusion in the squad.
Props Thomas du Toit and Vincent Koch and loose forwards Rynhardt Elstadt and Marcell Coetzee are in similar positions.
South Africa face defending champions New Zealand on September 21 in their opening World Cup Pool B match, then play Canada, Italy and Namibia.
South Africa (15-1)
Warrick Gelant; Sibusiso Nkosi, Jesse Kriel, Andre Esterhuizen, Dillyn Leyds; Elton Jantjies, Cobus Reinach; Marcell Coetzee, Rynhardt Elstadt, Siya Kolisi; Lood de Jager, RG Snyman; Vincent Koch, Schalk Brits (capt), Thomas du Toit
Replacements: Scarra Ntubeni, Lizo Gqoboka, Wilco Louw, Marvin Orie, Marco van Staden, Kwagga Smith, Faf de Klerk, Francois Steyn
Coach: Rassie Erasmus (RSA)