Morne Morkel may have bowled his last delivery at international level, with South Africa's retiring paceman trudging off the field on day three of the fourth Test.
Morkel, who announced prior to the four-Test series that he would retire after the series finale against Australia, suffered a side strain during his 13th over in Johannesburg.
The beanpole was unable to continue bowling and left the ground for assessment.
Team management has confirmed Morkel is dealing with a left side strain, the same injury he suffered in October.
Morkel was expected to spend six weeks on the sidelines on that occasion, but was only cleared to return after 11 weeks.
The Proteas say Morkel's side is being strapped and he will try to continue bowling in the match.
Morkel, who is expected to join a Big Bash League franchise for the 2018-19 season, produced career-best match figures of 9-110 in the third Test.
The 33-year-old's man-of-the-match haul didn't make him reconsider retirement plans.
"It is tough. Especially leaving a quality group of men in the change room. It is going to be sad but I suppose all good things come to an end," Morkel said.