Louis Oosthuizen has joined Justin Rose in withdrawing from this week's Honda Classic due to injury.
The South African has gone down with a recurrence of the back problem that has dogged him for several months.
It originally became an issue at last year's Open Championship when he was forced to pull out midway through the first round at Muirfield.
Oosthuizen looked in decent form at last week's WGC-Accenture Match Play Championship as he beat Nick Watney, Henrik Stenson and Webb Simpson to reach the quarter-finals before going down 2&1 to eventual champion Jason Day.
However, after that defeat to day he revealed his back complaint had flared up again, stating: "If I can commit myself to hit the shot it's not that bad, but I can't commit. My body is restricting me to go through the shot."
Oosthuizen has now returned to his home in Florida and will rest up for the next week in a bid to be ready to compete at the WGC-Cadillac Championship at Doral.