Stacy Lewis fired a 9-under 63 on Thursday to establish a 3-stroke lead after the opening round of the Honda LPGA Thailand.
Lewis, the 2012 LPGA Tour Player of the Year, was coming off a tie for 15th at last week's season-opening Handa Women's Australian Open.
"I would say coming off of last week I didn't hit it very well," said Lewis.
Karine Icher sits alone in second place after a first-round 66 at Siam Country Club's Pattaya Old Course, while Inbee Park, Catriona Matthew, Amy Yang and Gerina Piller are a stroke back in third.
So Yeon Ryu, Beatriz Recari and Lizette Salas all shot 68s to close the opening round knotted in seventh place.
A pair of notables occupy 10th place: 15-year-old amateur sensation Lydia Ko and last year's runner up Ai Miyazato. The former recently won the New Zealand Women's Open to become the youngest victor in Ladies European Tour history. It was the third professional victory for the amateur Ko, who finished third last week in Australia. Miyazato, meanwhile, was a 2010 champion at this event.
Ko and Miyazato both carded 69s and were joined by Karrie Webb, Se Ri Pak, Angela Stanford, Mi Jung Hur, Ariya Jutanugarn, Mika Miyazato, Caroline Hedwall and Ilhee Lee.
Jiyai Shin, who won in Australia last week and jumped to No. 6 in the world as a result, shot 70.
World No. 1 and two-time defending champion Yani Tseng carded five bogeys against just two birdies en route to a first-round 75. Tseng ended in second place last week.
Piller and Park went out with the early wave on Thursday and hit the clubhouse as the co-leaders, but Lewis and Icher had yet to make their moves.
Icher twice picked up back-to-back birdies during her outward nine and she gained another stroke at the par-4 13th to play herself into contention. She turned the trick again on the last to close at 6-under.
Lewis, though, eagled the par-4 third to set the tone early. After a par on the third, the world No. 3 tallied three straight birdies and added another on the ninth to close her front nine at 6-under.
Another birdie on No. 10 gave Lewis the outright lead and she never looked back. After picking up another shot on the 12th, Lewis stumbled to a bogey on the 16th, but she rebounded with back-to-back birdies to hit the clubhouse with a 3-stroke edge.
"I think I missed two greens all day. I just had a ton of birdie putts and I even left a few out there," Lewis said. "The fact that it could be lower -- I'm not complaining --- but it was just a great day. I made a couple key up and downs. It was pretty good."
NOTES: The field this week is comprised of 70 players -- 60 LPGA Tour players and 10 sponsor invites ... Michelle Wie finished second here in 2011 ... Last year, Tseng closed with a 6-under 66 to overtake Ai Miyazato. Tseng struggled to a 73 in round one, but came back with back-to-back 65s in the second and third rounds to rally back into contention. Tseng also won this title by five strokes in 2011.