Tseng, whose best finish since her 3rd place finish at the Honda LPGA event in March has been a 19th place finish at the LPGA Championship, produced 11 birdies in today's third round, the sort of form that saw her dominate the women's game through 2010, 2011 and much of 2012 before her game deserted her.
Tseng leads by three over Suzann Pettersen and Pornanong Phatlum with a group of four players including current world number two Stacy Lewis one further back.
Karrie Webb is the best of the Australians adding a second consecutive 67 today to move into a share of 8th position and five behind Tseng.
Other Australians, Sarah Jane Smith, Katherine Hull-Kirk and Sarah Kemp all made the cut but are well back in the field.
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