Ji Yai Shin fired a five-under-par 67 on Thursday to take a one-shot lead after the opening round of the Samsung World Championship.
Paula Creamer is just a stroke behind the Korean while two-time reigning champion Lorena Ochoa is in a group of six golfers another shot back at the Half Moon Bay Golf Links' Ocean Course.
The 20-year-old Shin gained membership on the LPGA Tour with a surprise win at the Women's British Open in August.
However, she opted to return to the Korean LPGA Tour following her major victory, notching a victory at the Shinsegae KLPGA Championship last weekend in her quest for the tour title.
A top-10 finisher in six previous LPGA events this season, Shin picked up steam on the back nine, ripping off four straight birdies starting at the 12th before settling for her only bogey of the round at the 16th.
A runner-up at the Samsung World Championship in 2005, Creamer fired five birdies in her round with her last coming at the 17th as she made up for her only bogey on the previous hole.
Ochoa, who claimed her seventh victory of the season in a playoff at the Navistar Classic last week, managed a three-under 69 despite two bogeys on her first six holes.
The world number one rebounded with an eagle on the par-five 10th and added her third birdie of the day on the 17th.
Ochoa is attempting to become the fourth player to win the event at least three times, including five-time winner Annika Sorenstam.
The Swedish star is also tied for third following the opening round after notching four birdies along with a bogey.
Ochoa and Sorenstam are tied with Na Yeon Choi, Yani Tseng, Song-Hee Kim and Angela Stanford.
Collated first-round scores (USA unless stated, par 72):
67 Ji-Yai Shin (Kor)
68 Paula Creamer
69 Ya-Ni Tseng (Tai), Na Yeon Choi (Kor), Annika Sorenstam (Swe), Lorena Ochoa (Mex), Angela Stanford, Song-Hee Kim (Kor)
70 Katherine Hull (Aus)
72 Jeong Jang (Kor)
73 Eun Hee Ji (Kor), Juli Inkster, Cristie Kerr
74 Karrie Webb (Aus), Suzann Pettersen (Nor)
75 Seon Hwa Lee (Kor), Hee-Won Han (Kor), Helen Alfredsson (Swe)
76 Angela Park (Bra)
77 In-Bee Park (Kor)
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