Ariya Jutanugarn shot 2-under 70 on Saturday to snare the lead from Stacy Lewis through three rounds of the Honda LPGA Thailand.
Jutanugarn, a Thailand native, is playing this tournament courtesy of a sponsor invite. She began the third round in second place and used a stretch of five straight birdies at the onset of her inward nine to grab the lead, eventually closing at 11-under 205.
The world No. 3 Lewis held a 3-stroke advantage through 18 and 36 holes, but she carded six bogeys on Saturday en route to a 76 at Siam Country Club's Pattaya Old Course. The 2012 LPGA Tour Player of the Year is now tied with Se Ri Pak (71) and Beatriz Recari (72) at minus-8.
World No. 4 Inbee Park recorded a 71 and grabbed sole possession of fifth place at 7-under, while world No. 8 So Yeon Ryu (74) dropped into a tie for sixth with Lizette Salas (73) at 6-under.
Na Yeon Choi, ranked second in the world, turned in her best round of the tournament with a 67 and moved into a tie for eighth with Gerina Piller (70) and Shanshan Feng (68) at minus-5. Catriona Matthew (76) and Amy Yang (70) are both a shot back.
Jiyai Shin, who won last week's season-opening Handa Women's Australian Open and jumped to No. 6 in the world as a result, is 3-under.
Fifteen-year-old amateur sensation Lydia Ko, who recently won the New Zealand Women's Open to become the youngest victor in Ladies European Tour history, is 2-under through 54 holes. She carded her worst round of the tournament thus far with a third-round 74.
Last year's runner up Ai Miyazato is also 2-under. A champion at this event in 2010, Miyazato turned in a 74 on Saturday.
World No. 1 and two-time defending champion Yani Tseng has shot rounds of 75, 68 and 72 to sit at 1-under. Tseng finished second last week in Australia.
Jutanugarn opened the third round with a birdie on the first and quickly found herself tied for the lead thanks to bogeys by Lewis on Nos. 3 and 6.
Lewis rebounded with a birdie on the seventh, then saw her advantage jump back to three when Jutanugarn made a mess of the par-4 ninth and stumbled to a double bogey.
But the inward nine belonged to Jutanugarn, who unfurled a scintillating stretch of five consecutive birdies beginning at the 10th. Lewis failed to match the run, bogeying No. 10 and birdieing the 13th, and when the dust had settled Jutanugarn was on top by two at 13-under.
"I did feel a lot of pressure early on. I felt the whole Thai people hope was on my back," said Jutanugarn. "After a few holes, people starting to cheer me up, and that made all the pressure gone away."
Jutanugarn, 17, didn't close particularly strong, with bogeys on three of her last four holes, but neither did Lewis, who ended with three straight bogeys to find the clubhouse at 8-under.
NOTES: Lewis tied for 15th last week in Australia ... Ko finished third last week ... Jutanugarn's sister Moriya, an LPGA rookie, is 10-over through 54 holes ... Michelle Wie finished second here in 2011. She is even through 54 holes.