Moriya Jutanugarn took the lead into the weekend at the LA Open in her latest bid to join younger sister Ariya as an LPGA Tour winner.
Jutanugarn shot a bogey-free five-under 66 on Friday at Wilshire Country Club to get to eight-under 134 in the LPGA Tour's first event in Los Angeles since 2005.
Katherine Kirk had an even-par 71 after an opening 69 to be the best-placed Australian - six shots off the lead.
Jutanugarn, the 23-year-old from Thailand, started fast with birdies on the par-5 second, par-4 third and par-3 fourth and added two more on the par-4 11th and par-5 13th.
Ariya Jutanugarn has seven tour victories.
Marina Alex was second after a 68.
So Yeon Ryu was six under after a 69, and fellow South Korean players Inbee Park (71) and Eun-Hee Ji (69).
Park was the first-round leader at 66. Lexi Thompson was three under after a 71.
Top-ranked Shanshan Feng followed her opening 74 with a 67 to get to one under.
Ariya Jutanugarn (71) was even par, and Michelle Wie (70) was one over.
Brooke Henderson, the Canadian star who won last week in Hawaii, had a 79 to miss the cut.
