Top-ranked defending champion Lydia Ko struggled with her putting while South Korea's Chun In-Gee sizzled late to grab a share of the lead after Thursday's opening round of the LPGA Kia Classic.
New Zealand's Ko needed a birdie-birdie finish to fire a two-over 74 to give the South Korean-born 19-year-old a share of 81st just a week before she defends a major crown at the ANA Inspiration at Rancho Mirage.
"I was hitting my drives really well. My long game was pretty good," she said. "I had a few miss-clubs and I couldn't make up and down on like 99 percent of the shots that I missed the greens."
Ko began on the back nine with a bogey. She answered with a birdie on 15 but stumbled with three bogeys in a row starting at the par-5 17th. She made another bogey at the par-3 sixth before her hot finish.
"I was struggling on the putting greens," Ko said. "It was really hard to get anything rolling when you're not putting that good."
Chun was among the last players to finish at the Carlsbad, California layout, with birdies on five of the last seven holes to shoot a six-under par 66 and match Americans Cristie Kerr and Mo Martin for the 18-hole lead.
"Greens were a little bumpy this afternoon so I stayed patient (and) so I made a good round," Chun said.
She will seek her third major title next week after the 2015 US Women's Open and last year's Evian Championship. The 22-year-old was runner-up to Ko at last year's ANA Inspiration.
Martin fired a bogey-free 66. She opened with a birdie, ran off three birdies in a row starting at the par-5 fifth and added birdies at the par-5 10th and 17th holes.
"Just had a really good putting day," Martin said. "I've been waiting for a good putting week and I had a good putting day today. It was great."
Kerr took her lone bogey at the second hole but birdied the third as well as all four par-5 holes, the par-3 14th and the 18th.
"I hit some close and made some longer putts. It was a good mix of stuff out there," she said.
"I had some long talks with my coach," she added. "I just needed to simplify my swing feel and not overcomplicate things. So kind of went back to some simple feels and played awesome."
Sharing fourth on 68 were France's Karine Icher, Americans Alison Lee and Marissa Steen, South Korea's Lee Mi-Rim and Kim Hyo-Joo and Thailand's Moriya Jutanugarn.