American John Mallinger posted seven birdies and an eagle to power to a four-shot lead after Friday's second round of the Frys.com Open in San Martin, California.
Searching for his maiden win on the Tour, Mallinger was flawless with a course-record equalling nine-under 62, remaining bogey-free through the opening two rounds to reach 14-under 128 at CordeValle Golf Club.
The 33-year-old pulled away from the leading pack when he knocked in an 11-foot putt for eagle on the 15th hole and then stepped on the gas with birdies on the 17th and 18th.
Venezuela's Jhonattan Vegas (67) and American Billy Horschel (65) finished the day tied for second at 10 under.
Australian overnight leader Nick O'Hern couldn't maintain his course record tying rage from the opening day, backing up his 62 with an even par 71 to share fourth place with Belgian Ryder Cup rookie Nicolas Colsaerts (68) and American Scott Dunlap (63) at nine-under.