Michael Putnam used a big back nine to surge up the leaderboard and shoot a 9-under 63 in Thursday's first round, giving him a 1-shot lead at the Humana Challenge.
Over the first three rounds, players will alternate between playing the Arnold Palmer and Jack Nicklaus Private Courses at PGA West along with La Quinta Country Club. Sunday's final round will be contested on the Palmer Course.
Francesco Molinari, the only non-American in the top 10, finished with an 8- under 64 and he is tied for second with Blake Adams, Mark Wilson, John Peterson and Scott Pinckney. Molinari and Adams played on the Palmer Course, Wilson and Peterson were on the Nicklaus Course and Pinckney played at La Quinta.
Defending champion Patrick Reed (La Quinta) fired a 7-under 65 and he is tied for seventh with Matt Kuchar (La Quinta), Jason Kokrak (Nicklaus) and Steve Wheatcroft (Palmer).
Playing in his first event since withdrawing from last season's BMW Championship, 42-time PGA Tour winner Phil Mickelson carded a 1-under 71 and he is tied for 89th.