Tiger Woods hits his drive on the 12th during the first round of the Farmers Insurance Open golf tournament at Torrey Pines Municipal Golf Course, Feb 5, 2015. [Photo/Agencies]

SAN DIEGO - In an ominous start to his season, Tiger Woods walked off the course after 11 holes Thursday at the Farmers Insurance Open because of tightness in his lower back that he attributed to a fog delay.

It was his third straight PGA Tour event that he missed the cut or withdrew, and the sixth time since 2010 that he withdrew because of injury.

"I was ready to go," Woods said. "I had a good warmup 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. That's just kind of the way it is."

The scene is becoming familiar. Billy Horschel noticed some discomfort with Woods early in the round. Before long, Woods was reaching for his lower back, and the grimace became more pronounced. On their 10th hole - the par-5 first on the North Course at Torrey Pines - Horschel picked up the tee for Woods and took the ball out of the cup for him when Woods made birdie.

Woods hit a safe shot to the middle of the green on the par-3 third hole. When it was his turn to play, he had caddie Joe LaCava pick up his ball marker. Woods waited for Horschel and Rickie Fowler to finish before shaking their hands, getting into a cart and driving to his car.

"It's tough to see a guy I look up to, a guy I consider a friend, to have issues with spasms," Horschel said. "It's tough to see him go, but he was in quite a bit of pain."

Nicholas Thompson had an 8-under 64 on the North Course and had a one-shot lead over Michael Thompson when play was suspended by darkness. Brooks Koepka, coming off his victory last week in the Phoenix Open, had a 66 on the North. The best score on the tougher South Course belonged to Jhonnatan Vegas, who shot 67.

Dustin Johnson, playing for the first time since his six-month leave for "personal challenges," holed out for eagle on No. 4 on the South Course as his lone highlight. He had five bogeys and was 2 over with one hole remaining.

But this day was all about Woods, which used to be typical at Torrey Pines because he has won the tournament seven times. Thursday was different. Several players came out of the scoring area and said, "What happened to Tiger?"

The answer - his "glutes" didn't activate - was perplexing.

Woods said at his unofficial Hero World Challenge in December and the Phoenix Open last week that he was at full strength. He blamed this injury on warming up, and then having to stand around in the cool Pacific air during the fog delay.

"It's just my glutes are shutting off," Woods said, sound more like a physical therapist than a 14-time major champion. "Then they don't activate and then, hence, it goes into my lower back. So I tried to activate my glutes as best I could in between, but they never stayed activated."