Junior Springbok captain Handré Pollard, who was named IRB Junior Player of the Year on Friday, and experienced Test hooker Adriaan Strauss will join the Springboks in Port Elizabeth on Sunday.
Pollard superbly led the South African Under-20s at the Junior World Championships in New Zealand. The Junior Boks twice beat the NZ U20s en route to the final, where they were edged 21-20 by England in Auckland on Friday.
Strauss has been a fixture in the Springbok squad since 2012 and missed out on the last three matches because of suspension. He is free to play again next weekend.
Seven players based in France and England have been released to their clubs and will not be considered for selection for next weekend's final Test in the Castle Lager Incoming Series, against Scotland at the Nelson Mandela Bay Stadium in Port Elizabeth.
They are Gurthrö Steenkamp (prop), Schalk Brits (hooker), Bakkies Botha (lock), Francois Louw (flank), Morné Steyn (fly-half), Wynand Olivier (centre) and Bryan Habana (wing).
"I've always rated Handré very highly and with Morné returning to France and Johan Goosen struggling with a knee injury, we decided to bring him in," said Springbok coach Heyneke Meyer.
"Adriaan has been with us since June 2012 and has played in every Test in the last two seasons. He knows our structures well and will slot back in with no hassle.
"We will still travel to Port Elizabeth with a strong squad and will only consider calling up more replacements if necessitated by injury. The players in the squad who have not yet featured in one of our three matches this month have worked very hard.
"I'm a believer in earning opportunities and I feel that some of them deserve a chance to play for the Springboks against Scotland as they've now become accustomed to how we play and won't let their country down."
Jurie Roux, CEO of the South African Rugby Union (SARU), explained that the Test against Scotland falls outside of the international window prescribed by the IRB.
"We have reached agreement with the South African provinces and certain clubs that their players may be made available for the match," said Roux.
"The French and English clubs have exercised their right to withdraw their players from the Test and we respect and understand that.
"All the matches during the Castle Lager Rugby Championship fall within the IRB window and players based in Europe and South Africa will be available for selection.
"Because of the special nature of the Japanese season and the way in which it is structured, we have worked with these clubs to have players available for Springbok duty on an individual basis. That means Schalk Burger, Fourie du Preez and JP Pietersen will be available for certain matches, as agreed with their clubs.
"All Rugby World Cup matches next year fall within an international window and therefore all South African qualified players based anywhere will be available for selection."
South Africa squad:
Forwards (16): Willem Alberts (Sharks), Schalk Burger (Stormers), Marcell Coetzee (Sharks), Lodewyk de Jager (Cheetahs), Bismarck du Plessis (Sharks), Jannie du Plessis (Sharks), Siya Kolisi (Stormers), Victor Matfield (Bulls), Teboho Mohoje (Cheetahs), Tendai Mtawarira (Sharks), Coenie Oosthuizen (Cheetahs), Adriaan Strauss (Cheetahs), Flip van der Merwe (Bulls), Marcel van der Merwe (Bulls), Duane Vermeulen (Stormers), Callie Visagie (Bulls)
Backs (14): Fourie du Preez (Suntory Sungoliath), JJ Engelbrecht (Bulls), Johan Goosen (Cheetahs), Cornal Hendricks (Cheetahs), Francois Hougaard (Bulls), Zane Kirchner (Leinster), Willie le Roux (Cheetahs), Lwazi Mvovo (Sharks), Ruan Pienaar (Ulster), JP Pietersen (Sharks), Handre Pollard (Bulls), Jan Serfontein (Bulls), S'bura Sithole (Sharks)