South African Louis Oosthuizen, the 2010 British Open champion, withdrew from the second round of the Masters due to injury, Augusta National Golf Club officials said on Friday.
Tiger Woods shoots 71; Cameron Smith early clubhouse leader at Masters
Oosthuizen, who was partnered with Tiger Woods and Chile's Joaquin Niemann, had been scheduled to go out in the afternoon wave at 1:41pm ET.
The nature of the injury was not disclosed but the South African had been seen grabbing at his back several times during Thursday's opening round where he laboured to a four-over 76.