Holland's Dewi Claire Schreefel - ranked 204th in the world - stunned a top-class field at the Sime Darby LPGA tournament in Malaysia, shooting a five-under-par 66 to share the lead after Thursday's opening round.
Schreefel shared the top spot with Choi Na Yeon of South Korea, who ranks 200 places above her, as well as Maria Hjorth of Sweden, ranked 20th, and Brittany Lang of the United States, ranked 30th.
World number one Yani Tseng of Taiwan and defending champion Jimin Kang of South Korea finished the day on two-under-par 69 at the $1.9 million event, which includes nine of the world's top 10 golfers.
Underdog Schreefel said she got off to a "solid start". On the fourth hole she made a long putt to save a stroke and keep her momentum going. And she made three birdies on the back nine.
"Just hit it pretty pure and made a lot of good putts and I missed a few short ones for birdie, too, so just solid rounds," she said, adding that she had no game plan for Friday.
"All I can do is play my game. I'm not going to change it because somebody else is in front of me or behind me," she said.
The leading quartet is one stroke ahead of American Paige Mackenzie and Spain's Azahara Munoz.
The highlight of the day came from Melissa Reid, who sunk a hole-in-one on the par-three fifth hole. The British player ended the day on one-over 72.
Choi said she felt "great" about her game.
"The course looks great, and I think right now everything suits me well," she said.
Lang, who was in the first flight of the day, stormed through her round and said it was an advantage to start early.
"I got off to a good start. Birdied hole three to get to one-under and just kind of sailed in," Lang said. "It just felt very effortless today."