Cape Town - Dale Steyn and Kagiso Rabada were both destroyed in the 3rd ODI against Australia at Kingsmead last Wednesday.
David Miller's heroic 118* meant that the Proteas emerged with a memorable four-wicket victory to clinch the series, but earlier in the day Steyn (2/96) and Rabada (1/86) both carded their most expensive figures in ODI cricket.
Despite the batting-friendly nature of the wicket, that would have been a concerning sign for the Proteas with their two chief quicks put to the sword like that as a Test tour to Australia beckons.
Both Steyn and Rabada were left out of the fourth ODI in Port Elizabeth as the Proteas rotated, and in stepped Kyle Abbott, who took his chance with a man-of-the-match display and figures of 4/40 (8).
Now, ahead of Wednesday's fifth and final ODI in Cape Town, Du Plessis and the South African selectors have a tough decision to make.
Both Steyn and Rabada could do with a spell in the middle to forget the horror of Durban, but it would be tough to leave Abbott out.
The top six is taken care of, with the only possible change being a fit-again David Miller replacing Farhaan Behardien.
There are then five places up for grabs, with the Proteas having backed all-rounders in positions seven and eight so far in the series.
That leaves room for three specialist bowlers, and presuming that one of those will be taken by a spinner in the form of Imran Tahir or Aaron Phangiso, there are just two spots left for the fast bowlers.
That would make it impossible to select all of Abbott, Steyn and Rabada.
The other option would be to remove one of the all-rounders - Dwaine Pretorius, probably - to accommodate an extra bowler.
Du Plessis, though, has spoken about how happy he is with the depth in the current batting line-up.
"We're looking at possibly playing both (Steyn and Rabada) tomorrow, whether that's going to happen or not we don't know ... Kyle had an amazing game so it's difficult to leave someone like that out," Du Plessis said.
The captain added that both Steyn and Rabada would recover ahead of next month's Test series in Australia.
"They are both guys with a lot of pride and they put a lot of emphasis on their performance," Du Plessis said.
"They were a little bit hurt after that game when there were quite a lot of runs scored but then they quickly saw that it happened to pretty much every bowler on the day and it was just one of those wickets."
"Test matches are a completely different format and there is a lot of time before the first Test ... there is still a lot of time for them to work on whatever they need to work on. They're both in a really good space."
Play on Wednesday starts at 13:30.