Brandt Snedeker and K.J. Choi forged their way to a one-shot lead but six-time event champion Tiger Woods lurks after the first round of the US PGA Tour event at Torrey Pines.
Defending champion Snedeker fired a seven-under-par 65 on the North course while Choi managed the same feat on the more difficult South course.
The pair lead by one shot over North course players Adam Hadwin, Luke List, Ross Fisher, Billy Horschel, Charles Howell III, Scott Stallings and Mike Weir plus Josh Teater, who scored his 66 on the South.
The 14-strong Australian tilt failed to really fire with John Senden (69 on South) and Stuart Appleby (69 on North) the pick of the bunch in a tie for 36th.
“It was a good start and I’m happy to be bogey-free,” Appleby said.
“I didn’t capitalise on all of my chances and didn’t give myself enough chances inside 15 feet to go really low.
“So it is a nice start but I have to go across to the difficult course tomorrow so we can’t get ahead ourselves.”
Woods shot a four-under-par 68 on the South course to be just three back in a tie for 20th as he shoots for an unprecedented seventh title at the event.
The 14-time major winner also claimed the 2008 US Open on the same layout.
After opening with a long birdie putt on the first, Woods found trouble on the fourth, taking double bogey after a wayward approach.
But he fired in five birdies and an eagle over the next nine holes to scare the top of the leaderboard before two late bogeys dropped him down a few pegs.
Snedeker continued his love affair with Torrey, going bogey-free on his round to move his combined score over seven starts in this event to an impressive 52-under-par.
“The golf course is in great shape and to play the way I played today was nice,” Snedeker said.
“It was a great day, but I realise we’ve got three more of them to go, and I’ve still got the hard course to go, so not too much excitement yet.”
Choi carded eight birdies and just a lone bogey to take his place alongside Snedeker at the top.
Debutant Scott Gardiner (-2 North), Aaron Baddeley (-1 North) and Marc Leishman (-1 South) were the only other Australians under par on the opening day.
Alistair Presnell (Even), Greg Chalmers (+1), Rod Pampling (+1), Jason Day (+1), Matt Jones (+2), Cameron Percy (+2), Steven Bowditch (+4), Robert Allenby (+4) and Geoff Ogilvy (+5) all have work to do to make the weekend.