South Africa fast bowler Marchant de Lange has a stress fracture in his back and will play no further part in the tour of England.
De Lange is the second member of Graeme Smith's touring party to have to return home before the start of first Test at The Oval on July 19, following wicketkeeper Mark Boucher's career-ending eye injury.
He will be replaced by seam-bowling all-rounder Albie Morkel.
"Marchant has been diagnosed with a lower-back stress fracture and will require at least six weeks' rest and rehabilitation," said South Africa physiotherapist Brandon Jackson.
"A bone scan was done after his lower-back pain worsened in the past week, showing inflammation in the bottom vertebrae of the spine."
Morkel, the 31-year-old older brother of South Africa seamer Morne, therefore has the chance this summer to add to his solitary Test cap.
He has experience of English conditions in county cricket, including a stint with Somerset during this summer's Friends Life t20.
"Albie is the ideal replacement for Marchant, because he comes into the squad with invaluable knowledge and experience of the UK conditions," said convenor of selectors Andrew Hudson.
"He has a good first-class record, and his ability to swing the ball and to contribute with the bat lower down the order gave us the extra incentive to rope him in."