Tiger Woods' former coach Butch Harmon has questioned the 14-time major winner's future after injury forced him to withdraw from the opening round of the Players Championship on Thursday.
Woods pulled out after playing just nine holes at Sawgrass in a six-over-par total of 42 to lie joint-last in the field. His appearance in golf's richest event was his first since suffering knee and Achilles injuries in the Masters last month.
After watching Woods' latest setback, Harmon said he thought a question mark now hangs over the 35-year-old, who has undergone four knee operations already in his career.
"I think his whole future is up in the air," Harmon said. "Does it mean he needs more surgery? If he does who knows what is going to happen."
Asked if he feared he was back to square one in his recovery, Woods - without a victory for 18 months and a major for nearly three years - replied: "I don't know. Give me a few days to see what the docs say.
"I'm surprised. The treatment's been good and it's been getting better. It just wasn't enough."
Woods has just over a month to try to get fit for the US Open and in normal circumstances would use the Memorial Tournament at Muirfield Village on June 2-5 as his one warm-up event.
However, the Players Championship was only his seventh start of the season and he has so far managed only two top-10 finishes, falling down to eighth in the world and now likely to fall even further this weekend.