LA JOLLA, California (Reuters) - Former world number one Tiger Woods withdrew after 11 holes of his opening round at the Farmers Insurance Open on Thursday because of a back complaint, with American compatriot Nicholas Thompson leading the way at Torrey Pines.
Woods, coming off his worst score as a professional at the Phoenix Open last week, had been favoring his back throughout his round after being forced to sit and wait out a lengthy fog delay.
The 14-times major winner, who continued to struggle with his swing and short game, was two-over-par on the North course when he decided to pull out, his third withdrawal in his last nine tournaments.
Thompson headed the field with an eight-under-par 64 on the North course, good enough for a one shot lead over Michael Thompson, who shot 65 on the same layout. Forty two players failed to finish their round before darkness fell.
Phoenix Open winner Brooks Koepka and Cameron Tringale shared third at six-under on the North, while Columbian Jhonattan Vegas had arguably the best round of the day as the only one of six players at five-under who played the South course.
Woods was due on the tee after an already lengthy delay before more Thursday fog rolled over the coastal course, causing another suspension.
"When we had that break. It just never loosened back up again. And when we went back out, it just got progressively tighter," Woods told reporters.
"It's frustrating that it started shutting down like that. I was ready to go. I had a good warm-up session the first time around.
"Then we stood out here and I got cold, and everything started deactivating again. And it's frustrating that I just can't stay activated."
FedEx Cup champion Billy Horschel, who was playing with Woods, noticed something was wrong early in the round and even started picking up tees for him.
"If I didn't see it on 10 (their first hole), I saw it on 11," Horschel said.
"Then I asked him when I walked off 12 tee, I said: 'back hurting you again?' He said: ‘Spasms'. It was unfortunate.
"He's a fighter. He wants to get the reps in, he wants to play well, and he kept trying to play through it, hoping that it would loosen up and I think it was getting there.
"It was real tough to see him walk and even make swings."
The 39-year-old Woods now has six withdrawals in 304 PGA tournament starts but all of them have come in the last five years.