Tiger Woods has been forced to withdraw from the Farmers Insurance Open after suffering with more back problems during his opening round.
The ailing former world No 1 was clearly in discomfort from the opening hole at Torrey Pines, and he was two over after 11 erratic holes before deciding he could not continue.
Woods, who missed much of last season after undergoing surgery to cure a pinched nerve in his lower back, needed a big week at one of his most successful venues to climb back into the world's top 50 after finishing joint-last at last week's Phoenix Open following the worst round of his professional career.
His much-publicised chipping problems resurfaced at the 10th - his opening hole - where he sculled a pitch 30 feet past the flag and two-putted for bogey, but he rediscovered his touch around the greens at the next as he chipped in from the rough to save his par.
The 39-year-old started grimacing after blocking his tee-shot to the par-three 12th way right as he dropped another shot, although he then scrambled well to get away with three straight pars despite his level of discomfort visibly increasing with every wayward drive.
Woods defied the pain to make a tidy birdie at the 16th, and he followed another two battling pars with a birdie at the first which dragged him back to level par for the day.
But his problems came to a head at the second hole on the North Course as he hacked his way to a double-bogey six, and he looked a forlorn figure despite managing to find the green at the par-three next.
Woods made his way gingerly to the green and asked caddie Joe LaCava to pick up his ball before he shook hands with playing partners Rickie Fowler and Billy Horschel and boarded a buggy back to the clubhouse.
Fog delay blamed
Before leaving the Torrey Pines car park, Woods spoke briefly to a swarm of reporters and blamed a two-and-a-half-hour delay prior to the start of his round for aggravating the injury.
Woods, a seven-time winner of the event, insisted he was warmed up and "ready to go" ahead of his original tee-time, but his lower-back muscles tightened as fog rolled in to hold up play.
"When we had that break, my back just never loosened back up again," Woods told reporters. "And when we went back out, it just got progressively tighter.
"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.
"It's just my glutes are shutting off. 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."
Fowler said it was difficult to watch Woods play and spoke of the physical toll the sport takes on the body.
"Obviously (it is) tough to see him struggle with getting off to a tough start and it seemed like stuff started to bother him," said Fowler.
"I'm not sure exactly what it was, but obviously I enjoy playing with him and it's just tough not seeing him have his best whether it's with his game or with his health.
"Golf may not be an impact or contact sport but the body takes a beating."