World number one Tiger Woods withdrew from the Honda Classic during the final round on Sunday at Palm Beach Gardens in Florida, citing a back injury.
Woods retired while playing the 13th hole at PGA National where he was five over par for the day and level for the tournament, having struggled to the turn in five-over 40.
"It's my lower back with spasms," Woods, 38, said in a statement. "It started this morning warming up."
He said it was the "same feeling" he had during The Barclays tournament last August, where he finished in obvious discomfort.
His withdrawal comes less than five weeks before the first major of the year, the Apr. 10-13 Masters at Augusta National.
Woods, whose career major tally of 14 is second only to Jack Nicklaus, said it was too soon to know whether he would be able to defend his title at the WGC-Cadillac Championship, starting in Miami on Thursday.
"It's too early to tell," he said. "I need treatment every day until Thursday to try to calm it down and we'll see how it is."
Woods last withdrew from a tournament at the 2012 Cadillac Championship. He cited an Achilles injury but it did not prove serious. He bounced back two weeks later to win the Arnold Palmer Invitational.
(Reporting by Andrew Both in Cary, North Carolina; Editing by Mark Lamport-Stokes)