American Brittany Lang carded a six-under-par 66 to take a one-stroke lead after the first round of the Mizuno Classic.
Lang, searching for a first win in four seasons on the LPGA Tour, started on the back nine and picked up two shots on her first two holes before adding another on the 17th to reach the turn in 33.
The 24-year-old then picked up two further birdies and an eagle on the par-five seventh before bogeying the eighth.
Lang leads Japan's Nobuko Kizawa and Park Hee-young of South Korea, who both carded 67s.
American Vicky Hurst, South Korean pair Bo Bae-song and Jeon Mi-jeong and Momoko Ueda of Japan are tied for fourth on four under, while defending champion Jiyai Shin is in a group of 13 players in a share of eighth place.
World number one Lorena Ochoa is five shots off the pace after carding a one-under 71.