Tiger Woods has pulled out of the Players Championship at Sawgrass midway through round one with a recurrence of his knee and Achilles tendon injuries.
The American, playing in his first tournament since suffering the injuries at the Masters in April, dropped six shots in nine holes before quitting.
"The knee acted up and the Achilles followed that, and then the calf started cramping up," said Woods.
"Everything started getting tight, so it's just a whole chain reaction."
The former world number one, who had only begun practising again on Monday, had hinted on Wednesday that he was not fully fit going into a tournament that is often referred to as golf's unofficial fifth major.
However, he added: "This morning, it felt fine during warm-up and then as I played it got progressively worse.
"[The doctors] said I could play. The more rest I get, the better it would be, obviously.
"It's a big event. I wanted to come back for it and play and unfortunately I wasn't able to finish."
The 35-year-old world number eight struggled from his opening tee shot which found the rough on the left and he walked off the first green with a bogey.
He then twice found water on the par-four fourth on his way to a triple-bogey seven before dropping further shots on the fifth and ninth holes to reach the turn in 42, 10 shots off the lead, before deciding to walk in.
Woods, who quit the Players Championship on the final day last year with neck trouble, said he initially suffered the injury to his left knee and Achilles while hitting from pine straw in the third round of the Masters at Augusta.
He missed last week's tournament at Quail Hollow to give his leg as much recovery time as possible, but now has just over a month to try to get fit for the 16-19 US Open at Congressional Country Club in Maryland.
Woods won the last of his major titles at the 2008 US Open and has not won a tournament since the Australian Masters in 2009.
Shortly afterwards he became embroiled in a sex scandal that forced him to take five months out of the game and ultimately led to a divorce from his wife.