South Africa captain Graeme Smith was concussed in an accident before the start of the fourth day's play against England in the fourth Test on Sunday.
South African media manager Gerald de Kock told reporters Smith was struck on the side of his head by a ball hit by coach Ray Jennings during the team's warm-up.
"He was taken for x-rays and a scan, and has been diagnosed with concussion," de Kock said.
"He will take no part in today's play, and will be reassessed tomorrow."
De Kock said Nicky Boje would captain South Africa in Smith's absence.
