Colombia's Camilo Villegas and American David Toms share the lead on nine under par after the first round of the Humana Challenge at La Quinta Country Club.
Villegas, starting on the back nine on the Nicklaus course, carded a flawless round featuring nine birdies, including five in his first seven holes.
And Toms, who was playing the La Quinta course, also completed an error-free round with nine birdies and no bogeys to join Villegas at the top of the leaderboard.
"It was a good day," Toms said after hitting 17 greens in regulation and taking just 27 putts.
"I've always though that La Quinta Country Club is one of the tougher courses in the rotation because the greens are fairly firm and it's a tight golf course.
"But the golf course is in such good shape that if you had birdie putts you could really start to make them, and that's what I did today.
"I had a lot of opportunities. I made a couple of long putts but I kept the ball in play all day and had a lot of birdie putts."
Villegas had never played in the tournament before but his decision to arrive early and play a practice round on each of the three courses certainly paid dividends.
"Guys, I'm struggling," Villegas joked to reporters as he tried to remember the holes and how he made each birdie.
"I was chatting with my amateurs, having a good time and just picking targets and hitting it. How about that?"
Bob Estes and Brandt Snedeker were among four players tied for third on eight under, but Phil Mickelson is 11 shots off the lead after a 74 which included a double bogey and triple bogey in the space of five holes.
The pro-am tournament, previously known as the Bob Hope Classic, has had a change of format this year.
Rather than the five rounds of previous years, where players were in groups of four made up of one professional and three amateurs, this year the tournament is played over four rounds, one each at the La Quinta, Palmer and Nicklaus courses before the final round is also played on the Palmer course.
