Tiger Woods has withdrawn from this week’s Arnold Palmer Invitational with a bad back and has said he is unsure whether he will be ready to play at next month’s Masters.

The world number one posted a statement on his website saying he told Palmer in person that he would not be able to defend the title he won last year.

“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.”

Woods has been plagued by back problems since last year but his condition has worsened over the past month. He failed to finish the Honda Classic at Palm Beach Gardens earlier this month, quitting after 13 holes in his final round.

Then he tweaked his back again at the WGC-Cadillac Championship in Miami a week later. The world number one said he was uncertain whether he would play at the Masters, starting at Augusta National on April 10th.

“It’s too early to know about the Masters, and I will continue to be evaluated and work closely with my doctors,” he said. “I feel badly that I won’t be able to play in this great tournament this week.”

The Arnold Palmer Invitational is one of Woods’s favourite events. He has won the tournament eight times, including in each of the past two years.