Captain Faf du Plessis says the fourth Test against England could well be his last on South African soil.
England currently lead the series 2-1 heading into the fourth and final fixture at the Wanderers on Friday.
The visitors wrapped up their biggest away win in more than nine years when completing the victory on the final day in Port Elizabeth.
They took the final four wickets to bowl their hosts out for 237 to claim victory by an innings and 53 runs.
It’s a defeat for South Africa that puts even more pressure on du Plessis.
After defeat in the third Test, he said: “I have committed until the T20 World Cup. There isn't a lot of Test cricket left this year: one massive Test where we need everyone to be as strong as possible, afterwards there is quite a big gap.
“I have said before, there is an opportunity to release some of the captaincy. Two Test matches in the West Indies, and the rest of the year is white-ball stuff.
“Most probably after that, Test cricket will be something that won't see me.
“That's a decision I will make then. For me now it's to be as strong as possible.”
England are made 1.80 (4/5) favourites with bet365 to wrap up the series in style in the fourth Test.
South Africa are available at 3.50 (5/2) to bounce back and draw level. The draw is priced up at 4.50 (7/2) with the same firm.
Plessis still focused on ending series strongly
Du Plessis, however, also underlined the importance of not leaving mid-series.
He added: “I don't think that's what's leadership is about. I felt that the team has needed a leader to stand up and guide the ship through a difficult time.
“If you leave the team when they need you most, that's not my style. I have been under pressure a few times and I've played my best innings under pressure.
“I can't leave the team when they need me most. We are in a transition but I can't do it forever. It has been chipping away at your character. For now, that's what we need. I think it will make it worse if I say I'm out.”