Faf du Plessis insists he still plans to continue as South Africa captain until at least the T20 World Cup but admits the fourth Test against England could be his last on home soil.
The Proteas trail England 2-1 with one match remaining in Johannesburg, having been thrashed by an innings and 53 runs at St George's Park on Monday.
It has been rumoured skipper Du Plessis could end his Test career after the four-match series, despite previously describing the limited-overs tournament in Australia later this year as "a crossroad in my career".
The 35-year-old said in his post-match presentation he had "heard the rumours of a possible retirement" but "nothing has changed".
However, speaking at a news conference, he recognised the Wanderers could see his final home appearance in the longest format, as he will not consider quitting mid-series.
"I have committed until the T20 World Cup," Du Plessis said. "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 [in July], 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."
Dismissing the idea of quitting before the fourth Test, he said: "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."
South Africa will be without suspended strike bowler Kagiso Rabada when they attempt to draw the series, but Du Plessis is also concerned by his batting unit.
The Proteas never threatened to push England in the third Test, their biggest partnership of the second innings by far a 10th-wicket stand of 99 between Keshav Maharaj (71) and Dane Paterson (39 not out).
"[Missing Rabada] is a big frustration, disappointment," Du Plessis said. "He's our best bowler, and it's not the first time that we've lost him in what will be a crucial game for us.
"We're already a little bit light on experience in our Test unit. He will be a huge loss - that's just the cards that we've been dealt. We've got to make the best of it. There's no using excuses for that.
"We have to regroup, have some firm chats over the next few days about where we need to get better, and make sure we move forward. We've shown signs of that.
"With the bowling, our controlling of the rate has been something we've been good at. Kesh [Maharaj] had a five-for, which showed this wicket was made for the spinners. There were a lot of wickets taken by the spinners.
"The same thing is happening with the batting unit - we're not putting on big totals. If you look at England, it's just one or two guys that put their hands up and score big hundreds.
"One big partnership gives you that momentum that you need, so we need to be better."