Vernon Philander withdrew from the second cricket test against Australia after waking up with soreness in his back Thursday, a significant setback for South Africa.
Team manager Mohammed Moosajee said the 27-year-old paceman "woke up complaining about lower back stiffness, he progressively got worse and didn't respond to the treatment from our physiotherapist."
Philander was due to have MRI scans, Mossajee said, "to give us a clearer indication of the symptom."
Rory Kleinveldt, who was initially dropped after the drawn first test in Brisbane last week, was reinstated to the starting XI for Adelaide.
Philander needed only seven tests to reach the 50-wicket milestone, the second-fastest in test history. He has 63 wickets in his first 11 tests, but struggled on a flat wicket at Brisbane.