Defending champion Tiger Woods will miss this week's Arnold Palmer Invitational and admits he does not know if he will line up in the Masters next month due to back trouble.
The world number one announced in a statement on his website that he would be unfit to play at the PGA Tour event at Bay Hill Club and Lodge in Orlando, which begins on Thursday.
He will hope to recover for the Masters, beginning at Augusta on April 10, but Woods could offer no reassurance he will play at the first major of the year.
The four-time Masters champion announced he was pulling out of the Palmer event by saying: " I personally called Arnold today to tell him that, sadly, I won't be able to play in his tournament this year.
"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.
"It's too early to know about the Masters, and I will continue to be evaluated and work closely with my doctors. I feel badly that I won't be able to play in this great tournament this week."
Woods suffered back spasms at The Barclays tournament last summer and the problem has persisted.
He has played just three events on the PGA Tour this year, and completed just two of those, having pulled out of the recent Honda Classic during his final round when injured.
The 38-year-old decided he was well enough to compete at the WGC-Cadillac Championship in Doral, Florida, days later, however he could not challenge on the final day after carding a 78.
Woods has won the Masters four times, but not since 2005.
He has not missed a Masters since making his debut as an amateur in 1995.