Los Angeles - Five-time major winner Phil Mickelson, back in action after more than three months and two surgeries, was delighted to fire a first-round 68 in the PGA Tour Career Builder Challenge on Thursday.
"I thought it was phenomenal," said Mickelson, who underwent surgery in October and December to repair a sports hernia and only began hitting balls a week ago.
"I struck it horrible, but I scored out of my mind, so I'm very happy with it," added the 46-year-old left-hander, who was four shots off the lead of tour rookie Dominic Bozzelli.
"My first round of golf was Saturday and I've been able to work out just the last two weeks," Mickelson said. "The last three months I haven't been able to do much at all."
Bozzelli had six birdies and a hole-out for an eagle two at the 14th hole of the Stadium Course, the toughest of three tracks in use over the first three rounds of the event in La Quinta, California.
Venezuela's Jhonattan Vegas, who claimed a memorable victory in the tournament in 2001 in his second start as a PGA Tour member, led a group sharing second on 65. He was tied with Patton Kizzire, Hudson Swafford and Harold Varner.
Varner's round at La Quinta included an eagle and six birdies. Swafford had eight birdies at La Quinta Country Club while Kizzire and Vegas both notched seven birdies without a bogey on the Nicklaus Tournament Course at PGA West.
Chilly, rainy weather - unusual for the California desert east of Los Angeles - greeted the morning starters.
But Mickelson said the tournament courses were the "perfect place" to launch his season.
"Around here you can get away with some mistakes and I was able to salvage a few pars with up and downs," he said.
Mickelson nabbed four birdies in the first nine holes at La Quinta, one of three courses in use for the tournament.
That included a 42-footer for birdie at the ninth. He saved par at 16 with delicate chip and run from the fringe, and followed his lone bogey of the day at 17 with a 10-foot birdie at the last.
In a tournament known for producing low scores, defending champion Jason Dufner opened with a one-under par 71 at La Quinta.
More rain was expected on Friday, and organisers moved up the tee times in hopes of completing the second round.
Leading first-round scores on Thursday in the PGA Tour Career Builder Challenge played on the La Quinta, Nicklaus Tournament and Stadium courses at La Quinta, California (USA unless noted):
64 - Dominic Bozzelli
65 - Patton Kizzire, Hudson Swafford, Jhonattan Vegas (VEN), Harold Varner
66 - Chad Campbell, Michael Kim, Boo Weekley, Ryan Blaum, J.J. Spaun
67 - Greg Owen (ENG), Paul Casey (ENG), Scott Stallings, Luke List, Scott Brown, Zac Blair, Geoff Ogilvy (AUS), Charles Howell, Brian Harman, Nick Watney, Danny Lee (NZL), Sean O'Hair, Seamus Power (IRL), Miguel Angel Carballo (ARG)