Ryan Gerrard logged a bogey-free 14 on Friday to take a four-point lead midway through the Barracuda Championship in Truckee, California.
The tournament at Tahoe Mountain Club's Old Greenwood course is the only PGA Tour event that uses the Modified Stableford scoring format. The highest score wins, with points awarded for double eagles (eight), eagles (five) and birdies (two). Pars are worth zero points, while bogeys are minus-1 and double bogeys or worse are minus-3 points.
Gerrard sits at 30 through two rounds, with Patrick Rodgers in second at 26 following an 11 on Friday.
Sweden's Vincent Norrman (second-round 12) holds third place at 23, with Beau Hossler (5) in fourth at 22. China's Zecheng Dou shot the best round of the day, a 16, to move into a tie for fifth with Sean Crocker (11).
First-round leader S.Y. Noh of South Korea followed up a 23 with a minus-5, leaving him tied for 12th at 18.
Gerard logged four birdies on the front nine and three on the back nine.
"I played really solid all day," said Gerrard, whose best previous finish in 15 career PGA Tour events was fourth place at this year's Honda Classic. "I've been hitting it great. I think I've hit 16 or 17 greens both rounds out here. So feel really comfortable at the altitude getting the distances to the right spot where I want 'em.
"I had a little bit of mud on my shirt from hitting it out of the water on six, but besides that, it was relatively stress-free and always nice to hole a few par putts coming down the stretch." Rodgers endured an up-and-down round with seven birdies and three bogeys, closing with back-to-back birdies.
"I'm doing a good job of making a lot of birdies, which is fun," Rodgers said. "I really enjoy this format. I feel like it frees me up. It's fun to play aggressive. It's fun to not worry about making mistakes, really try to attack a golf course."
Defending champion Chez Reavie, who won with 43 points last year, is tied for 23rd at 15 following an eight on Friday.