Louis Oosthuizen has been forced to pull out of next week's Alfred Dunhill Championship at Leopard Creek after having painkilling cortisone injections in his back.
The South African has struggled with a lower back problem this year and missed two months of action after withdrawing from the Open Championship - a tournament he won in 2010.
A course of injections to reduce pain and inflammation in the affected area has now ruled him out for two weeks.
"I was really excited to play in the tournament so it is very disappointing to miss out," the 31-year-old said.
"My back has been sore during the last few tournaments and it has been frustrating. I'm hopeful the injections will free up the problem and enable it to go away completely."
Oosthuizen, whose last victory came on home soil at the Volvo Golf Champions in January, aims to return at the Nedbank Golf Challenge in December.