De Villiers was, nevertheless, included in the starting XV Springbok coach Heyneke Meyer announced on Wednesday for the final of the four-nation tournament.
The influential leader will be given until Friday to recover from the sternum injury he sustained in their match against Scotland in Nelspruit last weekend.
"There has been good news, he had a scan on Tuesday and there is nothing broken and he is much better today but it is still a 50-50," Meyer said.
"We will wait until Friday before we make a decision... he is a warrior and hopefully he will be fit. I think we need him because it is going to be a really tough game.
"If Jean is not ready, Adriaan will captain the side. I’ve known him since he was a youngster and I thought he would be a great leader going forward and he has shown with the Cheetahs that he is a brilliant leader."
Meanwhile, Meyer made three changes to his pack of forwards for Saturday’s Test in Pretoria.
Two of the changes are among the loose trio, where Willem Alberts will also have to pass a late fitness test, while openside flanker Francois Louw moves back into the side after missing the weekend's Test for his wedding.
If Alberts was not cleared to play, Siya Kolisi -- who replaced Arno Botha early in the opening minutes of the side’s match against Scotland -- would take his place at the side of the scrum.
In the only other change to the run-on side, Flip van der Merwe replaced Juandré Kruger at lock.
"I thought Juandre probably played one of his best Test matches the past Saturday, it is to see if Eben Etzebeth and Flip can play together," Meyer said.
"At this stage we are very thin on number five locks and I don’t want to go into the Championship not having tested that [combination]."
Van der Merwe, better known as a number four lock, said there was not much difference between the two positions and he would be able to make the transition.
Meyer said Van der Merwe’s experience swayed him into rather going with this combination.
The breakdown areas had been a talking point this week after the match against Scotland and it was hoped that Louw’s inclusion as a specialist openside flanker would help remedy this area of play.
Meyer said the inclusion of Louw and Alberts was not a reflection of what he thought of Marcell Coetzee and Kolisi’s performances against Scotland.
"Francois Louw better understands how the Northern Hemisphere referees officiate the breakdowns and he is a recognised openside flanker," Meyer said.
"Francois and Willem were the loose forwards on the year-end tour with Duane Vermeulen and they really did well."
The Springbok mentor said the fact that he could bring back players like Louw and Alberts into the team demonstrated that he was building depth in his squad.
le Roux, 14. Bryan Habana, 13. JJ Engelbrecht, 12. Jean de Villiers
(captain) / Jan Serfontein, 11. Bjorn Basson, 10. Morné Steyn, 9. Ruan
Pienaar, 8. Pierre Spies, 7. Willem Alberts / Siya Kolisi, 6. Francois
Louw, 5. Flip van der Merwe, 4. Eben Etzebeth, 3. Jannie du Plessis, 2.
Adriaan Strauss, 1. Tendai Mtawarira
Substitutes: 16. Bismarck du Plessis, 17. Trevor Nyakane, 18. Coenie Oosthuizen, 19. Juandre Kruger, 20. Siya Kolisi / Marcell Coetzee, 21. Piet van Zyl, 22. Pat Lambie, 23. Jan Serfontein / Juan de Jongh