The Springboks will drop to fourth in the world rankings if they fail to beat Argentina in Friday's third-place play-off.
The positioning of all the teams remains unchanged following the World Cup semi-finals, with the Rugby Championship nations still occupying the top four spots.
However, the Boks and Pumas' rankings point tallies have decreased following their semi-final defeats to the All Blacks and Wallabies respectively.
South Africa's total shrunk from 86.80 to 86.02, while Argentina went from 85.07 to 84.24. The two will square-off on Friday for the bronze medal, and the winners of that match will finish the year in third spot.
Meanwhile, the World Cup finalists have consolidated their positions at the summit of the rankings. New Zealand earned 0.78 of a rating point, taking their tally to 93.67 at the top and second-placed Australia gained 0.82 of a point for a sum of 91.75.
World Rugby rankings (Top 20)
1. New Zealand 93.67
2. Australia 91.75
3. South Africa 86.02
4. Argentina 84.24
5. Wales 83.49
6. Ireland 81.17
7. France 79.77
8. England 79.77
9. Scotland 77.94
10. Japan 77.05
11. Fiji 76.96
12. Italy 72.74
13. Tonga 71.60
14. Georgia 71.45
15. Samoa 70.36
16. USA 68.66
17. Romania 66.59
18. Canada 62.65
19. Uruguay 62.11
20. Namibia 61.75
Full rankings
How the rankings work
Photo: Anne Laing/HSM Images