Ai Miyazato shot a 7-under 65 on Saturday to take a one-stroke lead over top-ranked Yani Tseng after the third round of the LPGA Thailand.
Miyazato, the Japanese player who won the 2010 tournament, birdied five of the first six holes on the back nine. She had a 14-under 202 total on Siam Country Club's Pattaya Old Course.
''I know everyone is going to try to be aggressive tomorrow,'' Miyazato said. ''If I can stay in my game until the last putt, I think I have a chance.''
Tseng, the winner last year, shot her second straight 65 after opening with a 73. The Taiwanese star had 12 worldwide victories last year, seven on the LPGA Tour.
''I really want to win this tournament,'' she said. ''To be a defending a champion would be great. I always really enjoy it out here to see a lot of fans and I'm very excited about tomorrow and looking forward to it.''
Australia's Karrie Webb and South Korea's Jiyai Shin were 12 under.
Webb shot a 71, and Shin had a 68.
Webb had a three-stroke lead Saturday morning after the completion of the lightning-delayed second round, playing the final four holes in 1 under after a 65.
Miyazato also returned early to finish the last five holes of her second-round 70. She has seven LPGA Tour victories, all in the last three seasons.
''It was a really, really long day for me,'' Miyazato said. ''I've been up since 4 o'clock this morning so it's been a while. But the temperature dropped down today so that helped a lot too. So that's why I think I could control myself out there.''
South Korea's Amy Yang was 11 under after a 68, and second-ranked Norwegian star Suzann Pettersen was another stroke back after a 69.
Thai amateur Ariya Jutanugarn had two eagles in a 65 that left her at 9 under.
Michelle Wie was even par after a 73.