Brandt Snedeker and KJ Choi carded seven-under 65s to share a one-shot lead after the first round of the Farmers Insurance Open on Thursday while Australians John Senden and Stuart Appleby are four shots off the pace. On a good day for scoring at Torrey Pines in San Diego, American defending champion Snedeker and South Korean Choi took advantage of the conditions with the former producing a bogey-free round. The in-form Charles Howell III is in a group of eight a shot back as 19 players managed scores of 67 or better. Played on two courses the South and the North the PGA Tour tournament also has Tiger Woods lurking at four under despite two late bogeys. Senden and Appleby were the best of the Australians as their three-under 69s saw them into a tie for 36th in San Diego. Scott Gardiner is at two under, while Marc Leishman and Aaron Baddeley are a further shot back in equal 72nd. Alistair Presnell (even par) is ahead of Rod Pampling, Greg Chalmers and Jason Day, who are all at one over. Matt Jones and Cameron Percy (both two over) made better starts than Robert Allenby and Steven Bowditch (both four over), while Geoff Ogilvy is tied for last on five over. Snedeker started on the back nine of the North Course, considered the easier of the two, and made four straight birdies from the 16th to the first to set up his round. The South Course may be tougher, but Choi was in fine form as he combined eight birdies with a bogey. Americans Josh Teater, Luke List, Billy Horschel and Scott Stallings join Howell, Canadians Adam Hadwin and Mike Weir, as well as Englishman Ross Fisher on six under. US Masters champion in 2003, Weir has the dubious distinction of having missed his last 17 cuts. Howell, who has two top-three finishes to his name in two starts this season, continued where he left off at the Humana Challenge. He made six birdies and two bogeys, as well as an eagle at the par-five first hole, on the North Course as he continued his streak of not having shot a round worse than 67 in 2013. Woods is competing on the PGA Tour for the first time this season and was inconsistent, making six birdies, two bogeys, an eagle and a double bogey. The 14-time major champion missed the cut at the Abu Dhabi Golf Championship last week but looks well-placed to make the weekend this time around. Nine Americans are locked at five under, while Vijay Singh and Ryo Ishikawa are among those a further shot back. Dustin Johnson (three under) is tied for 36th and American Phil Mickelson could only manage an even-par 72.