South Africa were forced to select 35-year-old veteran Frans Steyn at first-five for the decisive final game of the Rugby Championship against Argentina.

The Springboks were already missing their top two No 10s, Handre Pollard and Elton Jantjies, before stand-in Damian Willemse sustained a concussion in the 36-20 win over the Pumas in Argentina last Saturday.

That has forced coach Jacques Nienaber to give Steyn, an impact player off the bench for the last three years, a rare start on Sunday.

South Africa made one more change to their starting 15 by bringing flanker Pieter-Steph du Toit back for Franco Mostert.

Nienaber also reverted to a six-two split of forwards and backs on the bench for the game in Durban, meaning reserve halfback Faf de Klerk must also cover at first five-eighth if needed. Wing Kurt-Lee Arendse is the other back on the bench after serving a four-week suspension for a dangerous tackle on New Zealand's Beauden Barrett in the opening round of the tournament.

Hooker Bongi Mbonambi returns from injury for a place among the reserves.

Defending champion New Zealand and South Africa are tied on 14 points, with the All Blacks topping the standings on points difference.

New Zealand host Australia earlier on Saturday, meaning the Springboks will know the result of that game and what they need to do against the Pumas to win the title.

Australia and Argentina also have outside chances of winning the tournament.

South Africa: Willie le Roux, Canan Moodie, Jesse Kriel, Damian de Allende, Makazole Mapimpi, Frans Steyn, Jaden Hendrikse, Jasper Wiese, Pieter-Steph du Toit, Siya Kolisi (c), Lood de Jager, Eben Etzebeth, Frans Malherbe, Malcolm Marx, Steven Kitshoff.
Reserves: Bongi Mbonambi, Ox Nche, Vincent Koch, Franco Mostert, Duane Vermeulen, Kwagga Smith, Faf de Klerk, Kurt-Lee Arendse.