Michael Putnam made nine birdies in an 11-hole stretch Thursday and finished with a 9-under 63 to take a one-stroke lead in the Humana Challenge.
Putnam birdied Nos. 7, 9 and 10 on PGA West's Jack Nicklaus Private Course and ran off six in a row on Nos. 12-17.
Phil Mickelson had a 71 at La Quinta Country Club in his first event since the Ryder Cup.
Mark Wilson, Blake Adams, John Peterson, Francesco Molinari and Scott Pinckney were tied for second. Wilson, Adams and Peterson played the Nicklaus course; Molinari opened on the Arnold Palmer Private Course and Pinckney was at La Quinta.
Defending champion Patrick Reed had a 65 at La Quinta. He's coming off a playoff victory two weeks ago in the Tournament of Champions.