Na Yeon Choi, Suzann Pettersen and Jodi Ewart Shadoff all carded a 4-under 68 on Thursday to share the lead at the Kraft Nabisco Championship.
Ewart Shadoff held the outright lead with four holes to play at Mission Hills Country Club, but bogeyed the 16th to fall back into the tie.
Amy Yang and Anna Nordqvist occupied fourth place of the year's first major at 3-under, while world No. 4 Inbee Park is among a large group of players sharing sixth place at minus-2.
Choi, who is No. 3 in the world rankings, started on the back nine and opened with four straight pars before rolling in a birdie at the 14th.
She followed another par at the 15th with consecutive birdies at the 16th and 17th to move to 3-under.
Choi did not pick up another stroke from there, however, until she capped a streak of nine straight pars from the 18th with a birdie at the last to head to the top of the leaderboard.
"I'm really happy I played without a bogey today, but luckily I played in the morning today and the greens and fairways are a little softer than the afternoon," said Choi.
Pettersen also started on the back nine during her bogey-free round.
After opening her day with six straight pars, she reeled off three straight birdies starting at the 16th.
But like Choi, Pettersen recorded one birdie and eight pars through her inward nine to end at 4-under.
"Today was everything I could ask for an opening round," said Pettersen. "Just feeling really good all week, and it's just about kind of trusting what you have, and I couldn't ask for a better start."
Ewart Shadoff, meanwhile, countered a birdie at the third with a bogey at the fifth before hitting the turn at 1-under with a birdie at the eighth.
She then reeled off a string of four straight birdies from at the 11th to move into sole possession of first at 5-under, but it was short-lived after her bogey at the 16th dropped her back into a tie with Choi and Pettersen.
"I've been playing really consistently the last three or four tournaments," Ewart Shadoff said. "And so I knew my game is right there, and I knew I was due to have a really good round."
Jane Park briefly held a share of the lead after pouring in four birdies over a six-hole stretch starting at the fifth, but she closed with bogeys at the 12th and 15th to drop into the group of players at 2-under.
NOTES: World No. 2 Yani Tseng can reclaim the top spot from Stacy Lewis with a victory this week. Tseng won this event in 2010, finished second in 2011 and placed third in 2012 ... With a win this week, Se Ri Pak could join Louise Suggs, Mickey Wright, Pat Bradley, Juli Inkster, Annika Sorenstam and Karrie Webb as the only players to complete the LPGA's career Grand Slam ... Defending champion Sun Young Yoo finished her first round with an even-par 72.