Top-ranked Inbee Park birdied her final three holes Thursday for a 6-under 66 and a share of the JTBC Founders Cup lead among the early starters.
Coming off a victory two weeks ago in China in a Ladies European Tour event, Park closed with a tap-in birdie on the par-4 ninth after nearly holing a pitching wedge from 134 yards at Desert Ridge's Wildfire Golf Club.
"It was a very solid round," Park said. "Very good irons today."
Morgan Pressel was 7 under after eight holes in her afternoon round in perfect conditions with the temperature in the low 80s. She played her first six holes in 6 under, birdieing Nos. 10-13 and making an eagle on the par-5 15th, and also birdied the par-3 17th.
Defending champion Stacy Lewis, second-ranked Suzann Pettersen, 2011 winner Karrie Webb and Michelle Wie also played in the afternoon.
Gerina Piller matched Park with a 66. She has two top-10 finishes in four events this season.
"The more I can get in that position, obviously the more confidence I get," Piller said. "I just keep on reminding myself that I'm good enough to be out here and I have the shots and I just need to let myself do it."
Sixteen-year-old Lydia Ko was at 67 along with Jodi Ewart Shadoff, Mo Martin and Pornanong Phatlum. Playing alongside Park, Ko closed with a bogey after driving left into the desert.
"I normally eat more than I did today -- and I normally eat a lot, so that's saying something," Ko said. "I forgot to bring my food and my protein bars. That's my excuse."
Park had six LPGA Tour victories last season, sweeping the first three majors, and became the first South Korean to win the player of the year award. She took a break after the season and skipped the first two events this year, returning with a second-place finish in Thailand and a tie for fourth in Singapore.
"I was a little bit exhausted last year after all the things happened," Park said.
She made five of her seven birdies on her final nine holes.
"I was hitting the ball good all day, but just on the front the putts didn't seem like they wanted to go in," Park said. "I read a couple of putts wrong and, on the back nine, I had shots a lot closer than the front nine, and obviously I holed some putts on the back nine."
She three-putted the par-4 third for her lone bogey.
"That was my only mistake today," Park said.
Paula Creamer, a playoff winner three weeks ago in Singapore in the last LPGA Tour event, shot 70. She had a double bogey on the par-4 eighth, her 17th hole of the day.
"Just one bad swing on the tee shot and hit in the hazard," Creamer said.
DIVOTS: The Semper Fi Fund said Thursday that The Bob & Renee Parsons Foundation will match Cristie Kerr's tour earnings this year to help injured and critically ill service members and their families. Kerr is sporting a Semper Fi Fund logo on her bag. ... Piller recently switched putters and put a new driver and 5-wood in the bag Wednesday.