Springboks name four scrum-halves to play Romania
Cobus Reinach starts in the No.9 shirt with Grant Williams being promoted from the bench to the right wing in 14 personnel changes to the starting lineup after last weekend's opening win against Scotland.
Jaden Hendrikse and Faf de Klerk, who offers cover at fly-half, are on the bench for Sunday's match.
"People were surprised when we picked four scrum-halves in the squad but we knew they offered us the skills and versatility to provide backline options to manage the challenges that tournament rugby gives you," head coach Jacques Nienaber said in an SA Rugby statement.
"We have been rotating and testing players in different positions since last season to put us in the fortunate position to have a group of 33 players in France that are closely matched in terms of their quality of play and skills," he added.
Among the forwards, lock Jean Kleyn makes his fifth Springboks appearance, four years after representing Ireland in the last World Cup.
Hooker Bongi Mbonambi takes over the captaincy from emblematic back-rower Siya Kolisi, who guided the team to the Webb Ellis trophy in 2019.
It will just be the second Test between the sides after the Boks' victory at the 1995 World Cup.
The Oaks started this year's tournament with a heavy defeat to Ireland last weekend despite having opened the scoring after just three minutes.
"Romania are a patriotic team and they will be playing for their country," Nienaber said.
"It is a massive opportunity for them to play against us because such occasions are very rare, so they will give everything.
"They scored the first try in their opening match against Ireland, they showed real skill in a number of areas of their game, and they fought throughout the match, so we know what we are in for," he added.
After Romania, the Boks face world number one side Ireland on September 23 before finishing their Pool B campaign against Tonga on October 1.
South Africa (15-1)
Willie le Roux; Grant Williams, Canan Moodie, Andre Esterhuizen, Makazole Mapimpi; Damian Willemse, Cobus Reinach; Duane Vermeulen, Kwagga Smith, Marco van Staden; Marvin Orie, Jean Kleyn; Vincent Koch, Bongi Mbonambi (capt), Ox Nche
Replacements: Deon Fourie, Steven Kitshoff, Trevor Nyakane, RG Snyman, Jasper Wiese, Jaden Hendrikse, Faf de Klerk, Jesse Kriel
Coach: Jacques Nienaber (RSA)