Ryan Palmer fired a superb 10-under 62 to take a two-stroke lead at the Farmers Insurance Open as Tiger Woods and Rory McIlroy struggled to make inroads.
Palmer, the 2018 runner-up, capitalised on playing the North Course at Torrey Pines in California to move into 10 under and the outright lead.
The American made five birdies on the front nine and six in eight holes beginning at the 10th, before dropping a shot at the last.
Palmer holds a two-shot lead over Brandt Snedeker, who carded a five-under 67 on the South Course.
The eight best rounds of the day came on the North Course, with Palmer's the highlight.
Woods (71) and McIlroy played the South Course and were left in a tie for 17th at four under.
A seven-time champion of the event, Woods made a double bogey to start his round before following that up with five birdies and two bogeys.
McIlroy struggled to a one-over 73 despite being two under through 11, with bogeys at 12, 15 and 18 hurting his chances.
J.B. Holmes (69), Jhonattan Vegas (68), Sebastian Cappelen (71) and Matthew NeSmith (70) are tied for third at seven under.
Beau Hossler (66), Keegan Bradley (72), Zac Blair (66), Patrick Reed (69) and Harry Higgs (68) are a shot further back.
Jordan Spieth (70) and Jason Day (67) are among the group with Woods and McIlroy at four under, while defending champion Justin Rose (70) missed the cut after being left to rue his opening-round 75.