(CNN) -- Tiger Woods has raised fears he may be forced to miss the U.S. Masters at Augusta after withdrawing from the Arnold Palmer Invitational.
Woods announced Tuesday that he will not play at the event because of a persistent back problem which has troubled him since last year.
The 14-time major winner has struggled over the past month and failed to finish the Honda Classic at Palm Beach Gardens where he quit after 13 holes of his final round.
Woods, 38, tweaked his back at the WGC-Cadillac Championship in Miami a week later and is facing a race against time to be ready for the U.S. Masters, which starts on April 10.
"It's too early to know about the Masters, and I will continue to be evaluated and work closely with my doctors," said Woods, who has won at Augusta on four occasions.
"I feel badly that I won't be able to play in this great tournament this week."
Woods has won the Arnold Palmer invitational eight times, including the past two tournaments.
In a statement on his website, Woods revealed he telephoned Palmer directly to tell him he would be unable to defend his title in Orlando.
"I personally called Arnold today to tell him that, sadly, I won't be able to play in his tournament this year," Woods said.
"I would like to express my regrets to the Orlando fans, the volunteers, the tournament staff and the sponsors for having to miss the event.
"Unfortunately, my back spasms and the pain haven't subsided."