Patrick Reed fired a second 63 to take a two-stroke lead at the halfway stage of the Humana Challenge in California.
Another nine-under-par round, this time at La Quinta, leaves him with a clear advantage over fellow American Brendon Dodd who emulated Reed's 63 at the Palmer Course.
Reed dropped his first shot of the week at the second after he had birdied the first, and his charge began when he eagled the par-five fifth either side of birdies at the fourth and sixth.
Five more birdies after the turn followed as he moved onto 18 under par overall at the tournament formerly known as the Bob Hope Classic, played over three courses.
"When you go over to La Quinta, the fairways are much more narrow than they are here, so you're really focusing on small targets," Reed said.
"I just got off to a good start hitting it, so I built confidence through the first two holes."
Ryan Palmer currently sits third on 15 under par overall after a round of 65 on La Quinta, while American compatriot Charley Hoffman is a shot further back.
Bill Haas and James Driscoll are in a tie for fifth on 13 under par, Charlie Beljan is a shot back, and 1997 Open champion Justin Leonard and 2007 Masters winner Zach Johnson are two of eight players in a tie for eighth.
Keegan Bradley is two shots further adrift of that group on nine under par overall, but the 27-year-old provided the highlight of the day with his first ever hole in one on the PGA Tour at the 180-yard, par-three third hole on the Nicklaus Course.