World number one Tiger Woods will miss this week's Arnold Palmer Invitational and says he is a doubt for next month's Masters in Augusta.
The 38-year-old American revealed he has a back injury.
"It's too early to know about the Masters," said Woods. "I will continue to be evaluated and work closely with my doctors."
The Masters is the first major of the year and begins on 10 April at the Augusta National Golf Club.
Woods, a four-time Masters champion, announced he was pulling out of the Palmer event, which begins at Bay Hill Club & Lodge in Orlando on Thursday, because he has not fully recovered from the back strain he aggravated during his final round 78 in the WGC-Cadillac Championship earlier this month.
The injury also forced his withdrawal from the final round of the Honda Classic at the beginning of March.
"I personally called Arnold today to tell him that, sadly, I won't be able to play in his tournament this year," Woods said,
"Unfortunately, my back spasms and the pain haven't subsided."
Meanwhile, it has been announced that Torrey Pines Golf Course near San Diego will host the 2021 US Open.
It will be the second time Torrey Pines has hosted the tournament after Woods defeated Rocco Mediate after a play-off to win the title in 2008.