Brooke Henderson kept giving herself chances to run away from the field at the Lotte Championship in Hawaii.
Five strokes ahead early on the back nine, Henderson four-putted the par-3 16th for a double bogey and bogeyed the par-4 18th at Ko Olina.
She finished with a one over 73 to be nine under with a round to play.
Minjee Lee had a 73 to be the best-placed Australian in a tie for 41st at two over.
Katherine Kirk (72) and Rebecca Artis (73) are at three over while Hannah Green (77) slid down the leaderboard to be five over.
Seeking her sixth LPGA Tour victory, 20-year-old Canadian Henderson opened with bogey-free rounds of 68 and 66.
Mo Martin was second after a 72. The 2014 Women's British Open champ countered two bogeys with an eagle on the par-5 13th.
Japan's Nasa Hataoka had a 68 to join Inbee Park (71) at seven under.
Top-ranked Shanshan Feng was six under along with Lizette Salas (70).
Feng's 74 was only her second over-par round of the year.
Hawaii's Michelle Wie moved up 13 spots, to 18th, with a 69.
