Australian Minjee Lee was two shots off the pace as Lee Eun-Hee Ji of South Korea led the LPGA Thailand after a blistering opening round nine-under-par 63 on Thursday.
Ji won her fifth US LPGA Tour title in her previous event last month, the season-opening Tournament of Champions in Florida.
She picked up right where she left off, in Chonburi.
After an opening birdie and a bogey on the third hole, Ji birdied nine out of the following 14 holes on the Siam Country Club Pattaya's Old Course.
Lee shot a 65 and had a share of second along with Danielle Kang of the United States, and Jenny Shin of South Korea.
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"I felt really great. I didn't miss any fairways and missed just two greens," Ji said. "I have a lot of confidence.
Lee was bogey free as she eagled the 15th and birdied five holes on a humid day.
"I was little bit slow starting out. I finished with three birdies on the last three holes at the front nine, and got a little bit better momentum," Lee said.
A group of four, three strokes off the lead, included Americans Jennifer Song and Lizette Salas, Canadian Brooke Henderson, and Australian Katherine Kirk.
World No.1 Ariya Jutanugarn, the 2013 runner-up, carded a 4 under 68, mixing an eagle and six birdies with two bogeys and a double bogey.
