LA JOLLA, January 24, 2014 (AFP) - Cink, seeking his first win since his 2009 British Open triumph, played without a bogey on the Torrey Pines North Course, the easier of the two layouts in use for the tournament.
He had a one-shot lead over fellow American Gary Woodland, whose 65 on the North Course included an eagle and five birdies.
Australians Jason Day and Marc Leishman, South African Tyrone Van Aswegen, and American Jim Herman shared third on 66.
American Pat Perez's 67 was the best of the day on Torrey's tougher South Course and left him tied for seventh alongside South Korea's Bae Sang-Moon, and D.A. Points.
Defending champion Woods, seeking a ninth career title at Torrey Pines, had two birdies and two bogeys in an even-par 72 on the South Course, which played almost four shots harder than the North on average.
Woods' eight prior victories at Torrey Pines include his 2008 US Open triumph. That was his 14th major title, and his pursuit of Jack Nicklaus's record of 18 majors has been stalled there ever since.
Woods has won the US PGA Tour event at Torrey seven times, and a victory this week would give him a third US PGA Tour event in which he owns eight titles. Woods has won both the Arnold Palmer Invitational and World Golf Championships Bridgestone Invitational eight titles.
Woods, who won by four strokes last year, rolled in a short birdie putt at the second hole. But he bogeyed the fifth from a bunker.
Woods found a greenside bunker at the par-three 11th, blasting out to 10 feet before two-putting for bogey.
He got back to even par with a birdie putt from just off the green at 14.
"Even-par is not too bad," said Woods, who was tied for 63rd. "I didn't play the par-fives worth a damn today, that's paramount on the South Course.
"I didn't do that, so consequently, I didn't finish under-par."
Cink got off to a quick start with three birdies in the first four holes.
Birdies at 11 and 13 were followed by a burst of three straight birdies from the 15th through the 17th.
"I've been playing fairly well this year. I've been feeling confident, so I'm looking forward to the challenge (of the South Course)," Cink said. "It's a good golf course to test yourself and see where you stand this time of year."
Local favorite Phil Mickelson, a resident of nearby Rancho Santa Fe and winner of this tournament in 2000 and 2001, carded a 69 on the North Course while battling a stiff back.
"I just think I'm getting old," Mickelson said. "If I overdo it it just gets a little tight."
Leading first-round scores on Thursday in the $6.1 million US PGA Farmers Insurance Open (USA unless noted):
64 - Stewart Cink
65 - Gary Woodland
66 - Jason Day (AUS), Tyrone Van Aswegen (RSA), Marc Leishman (AUS), Jim Herman
67 - Pat Perez, D.A. Points, Bae Sang-Moon (KOR)
68 - David Lynn (ENG), Steven Bowditch (AUS), Justin Thomas, Trevor Immelman (RSA) Jhonattan Vegas (VEN), Harrison Frazar, Noh Seung-Yul (KOR)
69 - Charley Hoffman, Nicolas Colsaerts (BEL), Erik Compton, Keegan Bradley, Phil Mickelson, Brendon Todd, Bobby Gates, John Merrick, Martin Laird (SCO), Brad Fritsch (CAN), Kevin Tway, Michael Putnam