South Africa fast bowler Friedel de Wet has been ruled out the final Test against England after suffering a recurrence of a back problem.
De Wet aggravated the injury in the third Test draw in Cape Town and will now sit out the decider at the Wanderers in Johannesburg on Thursday.
That means left-armer Wayne Parnell could be set to make his Test debut, having previously played nine one-day internationals.
"Friedel won't be training with us this week and, sadly, it's the long-term problem with his back again," South Africa coach Mickey Arthur said.
"I really feel for him, it happened in the fifth over of the first innings in Cape Town, but he came in and gave it his all with injections and a serious back injury for another 20-odd overs. It speaks volumes for him."
The 20-year-old Parnell has picked up 22 wickets in nine ODIs, while he is known to England fans after a successful spell at Kent.
And Arthur believes Parnell can rise to the occasion if he is selected on Thursday.
"Wayne is a huge talent, he bowls with pace, is a decent batsman and a good fielder," Arthur said.
"He has a real chance of playing because of his pace, we said we wanted three strike bowlers and Wayne could be one of them.
"Although he's very young in terms of first-class cricket, he will mature and I'm very happy to have him on board."