Last year's top-ranked amateur, Ariya had seven birdies — including five straight from No. 10 — for an 11-under 205 total at the Siam Country Club Pattaya Old Course. The 17-year-old Thai needed a sponsor's invitation to enter the tournament in her first year as a professional.
Stacy Lewis (76), Se Ri Pak (71) and Beatriz Recari (72) followed, and Inbee Park (71) was another stroke behind. Lewis, the third-ranked American, finished with three bogeys to lose her three-stroke lead after the second round.
Ariaya wants to stay composed in the final round.
"I went to the course today (under) pressure as there were so many fans coming to see me," said Ariya, who is bidding to become the first Thai player to win an LPGA tournament. "Not only my family, but also the entire country has hopes for me. But after I heard their hands clap, it became an inspiration."
Defending champion Yani Tseng, the No. 1 player in the world, shot a 72 for a share of 24th place.
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