Tavatanakit is aiming to become the second Thai player to win the tournament since it began in 2006.
Standing at 16-under after three rounds, Tavatanakit gained some separation from the field on Saturday, thanks to a round that saw her sink four birdie putts and add an eagle in the first seven holes.
Her co-leader after 36 holes, Madelene Sagstrom of Sweden, shot a 69 to come in at 13-under and lies second.
Another shot back and in a tie for third are Norway's Emily Kristine Pedersen (65 on Saturday) and a pair of South Koreans, Hye-Jin Choi (65) and Hyo Joo Kim (69).
Five women are in a logjam at 11-under and tied for sixth place -- amateur Suvichaya Vinijchaitham and Ariya Jutunugarn of Thailand, Canada's Brooke Henderson, Albane Valenzuela of Switzerland and Sei Young Kim of South Korea.
The top Australian is Grace Kim, who's tied for 16th place on nine under after a third-round 68, while Hannah Green is joint-41st on five under after a 70, Sarah Kemp joint-46th on four under after a 68 and Steph Kyriacou joint-55th on three under after a 72.
On another sizzling day in Choburi, the players had to fight through 90-degree temperatures.
"I'm really proud of my performance today," said Tavatanakit, who is aiming for her second LPGA Tour career win. "It's getting very tiring, exhausting in the heat. I'm just going to conserve my energy and take on the challenge tomorrow."
She is looking for consecutive wins after her victory last week at the Saudi Ladies International on the Ladies European Tour.
"Feel like last week gave me a lot of confidence going into tomorrow. I'm not saying I'm going to guarantee the result right away, but there is a lot of positives and a lot of good things to look at the past seven rounds I've played," she said.
34°C