Johan Goosen will start his first Test for the Springboks when he runs out at fly-half against Australia at Loftus Versfeld in Pretoria on Saturday.
The inclusion of the 20-year-old Cheetahs pivot in the place of Morné Steyn is one of three changes to the starting XV from the Springbok team that played New Zealand in Dunedin.
Goosen is one of the six players in the matchday 22 that are 21-years-old or younger - the others being Eben Etzebeth, Marcell Coetzee, Pat Lambie, Elton Jantjies and Jaco Taute.
The Western Province lock pair of Etzebeth and Andries Bekker will start in the middle row. Etzebeth is back in the Springbok team after missing the previous Test because of a suspension.
Springbok coach Heyneke Meyer, in announcing his side to face Australia on Wednesday, also made four changes on the bench, where Coenie Oosthuizen, Flip van der Merwe, Jantjies and Taute have been included.
Jantjies and Taute have not played Test rugby for the Springboks, while Oosthuizen is back from injury. Van der Merwe and Bekker swap places in the matchday 22.
"I've maintained from the outset that I won't rush Johan, but I feel he is now ready to start a Test for South Africa and I'm excited to see what he can bring," said Meyer.
"Morné (Steyn), in the last four seasons, has played close to 140 matches at Test, Super Rugby and Absa Currie Cup level and probably deserves a break, but this also provides a great opportunity for Johan, a player I rate very highly.
"Morné is a quality player and a fighter and I know he will bounce back."
Commenting on the changes at lock, Meyer said: "It's good to have Eben back with us. Flip played very well in Dunedin, but he's been struggling with an injury this week and that is why we decided to start with him on the bench. I also thought Andries did very well when he came on against New Zealand and he is an excellent jumper in the lineout as well."
Frans Steyn, who has been struggling with an ankle injury, has been bracketed with Taute in the midfield. Should Steyn not pass a fitness test by Friday, Taute will start and Juan de Jongh will come in on the bench.
The Springbok starting XV, with Frans Steyn at inside centre, boasts a combined total of 468 Test caps, with 314 of those belonging to the backs and 154 to the forwards.
Meyer said the Springboks were looking forward to Saturday's Test and realised the importance of the match.
"It's great to be back home in South Africa after three tough matches on the road. We were not happy with the results in Mendoza, Perth or Dunedin and we know how big the Test at Loftus Versfeld is on Saturday," said Meyer.
"The Australians will be tough opponents on Saturday. We've now lost our last five Tests against them and need to turn this around."
South Africa: 15 Zane Kirchner, 14 Bryan Habana, 13 Jean de Villiers (c), 12 Frans Steyn/Jaco Taute, 11 Francois Hougaard, 10 Johan Goosen, 9 Ruan Pienaar, 8 Duane Vermeulen, 7 Willem Alberts, 6 Francois Louw, 5 Andries Bekker, 4 Eben Etzebeth, 3 Jannie du Plessis, 2 Adriaan Strauss, 1 Tendai Mtawarira.
Replacements: 16 Tiaan Liebenberg, 17 Coenie Oosthuizen, 18 Flip van der Merwe, 19 Marcell Coetzee, 20 Elton Jantjies, 21 Jaco Taute/Juan de Jongh, 22 Pat Lambie.
Date: Saturday, 29 September
Venue: Loftus Versfeld, Pretoria
Kick-off: 17:00 (15:00 GMT)
Referee: Alain Rolland (Ireland)
Assistant referees: Romain Poite (France), Greg Garner (England)
Television match official: Shaun Veldsman (South Africa)