Masters champion Trevor Immelman pulled out of the Players Championship on Saturday because of "illness".
Although PGA Tour officials did not have specific details of the South African's ailment, they said he had already returned to his American home in Orlando.
Immelman, who became the first South African to win the Masters since Gary Player in 1978, has been replaced in the 144-man field by 23-year-old American Dustin Johnson.
In the build-up to this week's tournament at Sawgrass, Immelman said he needed to spend some time away from the game after battling for form since claiming his first major title.
He has missed the cut in his last two PGA Tour starts and had planned to take time off with his family after the tournament.