(Reuters) - Stewart Cink, seeking his first PGA Tour title in five years, charged into an early two-shot lead at the Farmers Insurance Open on Thursday while Phil Mickelson also moved into contention despite nursing a troublesome back.
Cink, who has not triumphed anywhere since his playoff victory in the 2009 British Open at Turnberry, fired a flawless eight-under-par 64 on the easier North Course, one of two layouts hosting the PGA Tour event.
That left him two ahead of Australian world number 10 Jason Day and South African Tyrone Van Aswegen, who both started out on the North layout at picturesque Torrey Pines Golf Club outside San Diego.
Mickelson, who often winced after hitting shots because of muscle pain down his side, carded a 69 on the North while seven-times winner Tiger Woods was eight strokes off the pace with three holes to play on the brutal South Course.
Tour veteran Cink was delighted with his opening round, despite totalling just one birdie on the four par-five holes.
"If you drive it well on the North Course, you're going to have birdie opportunities and I drove it very well most of the day," the 40-year-old American told Golf Channel after starting his round on a gorgeous, sun-splashed morning.
"It was just a different game from the short grass out there. You've got some shorter holes and I took advantage of a lot of those holes ... the par-fives, I didn't play those very well. It was a very calm, very relaxed kind of round."
Cink, a six-times winner on the PGA Tour, knows he will face a very different challenge on the South Course in Friday's second round.
"It's definitely a tale of two golf courses here," he smiled. "The South we all know is one of the most difficult courses on the tour and it pretty much requires all facets of the game to be on.
"I have been playing fairly well this year … so I am looking forward to the challenge. It's a big golf course to really test yourself and see where you stand this time of year."
San Diego native Mickelson, a three-times champion at Torrey Pines, mixed four birdies with a lone bogey to climb the leaderboard and was thankful he had played his opening round on the less daunting North Course.
"I kind of milked my way around the golf course and I was able to do that on the North Course because the penalty wasn't as severe as it is on the South," the American left-hander said.
"I am able to kind of get it up by the green and get up and down and salvage par. I made a couple of birdies but it won't hold up on the South Course so I've got to get it better."
Asked to explain what was wrong, Mickelson replied: "From the top (on the swing), it just kept locking up and giving me a shooting pain. I kind of flinch.
"If I overdo it, it's just prone to getting a little bit tight. It's just a muscular thing. My back feels fine, it's just a muscle on the side. I think it will go away in a short period of time. I don't think it's anything serious."
American Pat Perez opened with a 67 on the South Course while England's David Lynn birdied his final hole on the North for a 68 to finish level with Australian Steven Bowditch and American Justin Thomas.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue)