Steyn's return would bring a dilemma for South Africa
If Dale Steyn is fit, he will play and that's all there is to it. He is guaranteed his place in the South African Test XI on reputation and rightly so. He is 15 wickets away from overtaking Shaun Pollock as the country's highest wicket-taker, has an average a shave over Allan Donald's and strikes fear into batsmen with nothing more than a sharp stare.
Add to that his ability to swing the ball, his pace and his accuracy and he should be part of the side every time it takes the field unless - and it seems wrong to even contemplate it - the situation demands something else.
Steyn's recent injury record (nine times in the last two-and-a-half years since the 2013 Champions Trophy) has seen him miss four of the last six Tests. South Africa have had to find a way to function without him. In India, after Steyn sustained a groin strain in the first Test, they gave him until the first morning of each subsequent Test to prove his fitness. It spoke volumes about their optimism that he might play.
At some point in those seven weeks, team management must have known the extent of Steyn's strain and the slim chances that gave him of playing at all. When that became clear, they should have ruled out of the series, as they did Vernon Philander, and sent him home to recover but he was kept in the squad. Perhaps it was so India remained wary that he could become a factor. Perhaps they are doing the same thing now - only this time they don't have to.
Without Steyn, South Africa have sufficient options, especially as they packed their squad with five other fast bowlers. Between them they have the combinations to cover for Steyn's absence and, after the Newlands' Test, all of them have proved their worth.
That will making picking a pack even trickier if Steyn is fit, so much so that maybe not even Morne Morkel is guaranteed his place.
Morkel showed glimpses of his ability to lead the attack in Nagpur, where he found reverse swing, but he has since seemed more of a background bowler, although they may not be his own doing.
At Newlands, he was under-utilised at key moments to the extent that he was not even given the second new ball. That could have been a tactical decision by Hashim Amla, the former captain, but it could also have been a reaction to Morkel's workload. After the match, coach Russell Domingo said Morkel was "in the red zone" after bowling more than he should. After playing in the last five Tests and compensating for Steyn's absence, it could mean Morkel is due a rest and, even though South Africa would not want their fortunes to rest in inexperienced hands, that may not be a bad idea.
At the Wanderers, Morkel is not South Africa's most potent weapon. Although the surface offers pace, bounce and carry, Morkel does not always get the desired results. Instead, for someone in the Morkel mould, South Africa should look to Hardus Viljoen, the Bullring's homeboy, whose first-class record there is unmatched. Viljoen has bowled just 42 balls less than Steyn at the venue, has one more wicket than Steyn and a better average. In the first two franchise games this season, Viljoen took 20 wickets at an average just over 14.
In previous seasons, Viljoen has been complemented by Chris Morris, who has since moved to the Titans. He has bowled 80 overs less than Steyn at the Wanderers and averages slightly better than Viljoen. Morris did not look the part in the first innings at Newlands but redeemed himself in the second. His yorker-length deliveries were particularly impressive and he also gives South Africa a slightly longer batting line-up.
Then there is Kagiso Rabada, whose home Test debut at Newlands was overshadowed by other events like Hashim Amla's double hundred and Temba Bavuma's maiden century. He is also familiar with Wanderers. Rabada has not even bowled half as much there as Steyn or Viljoen but he has the best average among all of them.
Compare him with Kyle Abbott, who has played about the same amount of cricket at the Wanderers as Rabada, and it is clear who the better choice is.
In conclusion, even though Abbott is no longer carrying a hamstring niggle, he would be the man to leave out whether or not Steyn is fit. But everything else is not so clear.
South Africa would probably not want to go into a must-win game with an attack as inexperienced as Viljoen-Morris-Rabada. They may consider propping it up with the addition of Morkel and leaving out the spinner, Dane Piedt, as a consequence if they do not believe the surface will require a slower bowling option but that is unlikely.
In all likelihood, Morkel will have to play and the choice will be between two of Viljoen, Morris or Rabada. If Steyn is fit, only one of those three can play and there is then the additional risk of including Steyn as well.
The last thing South Africa want is for him to break down and they have reason to be concerned that he will. Apart from the two washouts in Bangladesh, the last time Steyn got through a Test was a year ago, against West Indies.
With the series result on the line, the time might have come to look at that reality.
Firdose Moonda is ESPNcricinfo's South Africa correspondent