TAIPEI, October 24, 2013 (AFP) - The Norwegian finished three shots better than Irene Cho, Caroline Hedwall, Karine Icher and Alison Walshe who were tied in second after the first round of the $2 million event.
"It was a tough day out there, conditions were not great," Pettersen said, following her round at the Sunrise Golf & Country Club in northern Taoyuan county.
"Four-under is a decent day. I felt like I put myself in a good position."
The 32-year-old has strung together nine top-10 finishes in her past 10 LPGA events, including back-to-back victories at the Safeway Classic and the Evian Championship.
She is closing in on world number one Park In-Bee, who finished a disappointing 28th at last week's KEB-HanaBank Championship in South Korea and is not playing in Taiwan this week.
Taiwanese star Tseng Yani, who was playing on the course where she grew up learning the game, recorded a disappointing four-over-par 76.
"The winds came up and down and sometimes it was big and sometimes not as strong," she said.
"I struggled a little bit from a hundred yards in, and then I had four three-putts, well, I'm not really happy with the score, but I will keep trying."
The 24-year-old, who has won 15 career LPGA titles, was tied for 47th.
World number six Choi Na Yeon, Michelle Wie and Lexi Thompson were in 21st after all shooting 74, with world number nine Catriona Matthew trailing one shot further back.
A total of 78 players are competing in the four-day event which has a top prize of $300,000.