The sixth-ranked Stosur lost serve three times, but managed to break her Thai opponent four times to claim victory and set up a match against Misaka Doi of Japan.
In other first-round action, third-seeded Angelique Kerber of Germany beat wild card Kurumi Nara of Japan 6-2, 6-1, and fourth-seeded Petra Cetkovska defeated last year's runner-up Kimiko Date-Krumm of Japan 6-2, 7-6 (2).
Sixth seed Ayumi Morita kept the hosts interest alive with a hard-fought 7-6(7-3), 6-2 win over Zhang Shuai of China but it was heartbreak for Shuko Aoyama, who went down 2-6, 0-6 to Yaroslava Shvedova of Kazakhstan in the first round matches.
Andy Roddick reached the third round of the Shanghai Masters on Tuesday, scoring battling 7-6 (7-3), 7-5 win over Bulgaria's Grigor Dimitrov.
The American 10th seed won a first set tie-break and sealed victory after clinching a topsy-turvy second set that contained five breaks of serve.
After Dimitrov broke Roddick in the ninth game of the second set to lead 5-4, the American smashed his bag repeatedly in frustration but he immediately broke back to level at 5-5. Earlier, Germany's Florian Mayer, the 15th seed, beat former world number three David Nalbandian 6-3, 6-4 to reach the third round and seventh seed Nicolas Almagro defeated Spanish compatriot Tommy Robredo 7-5, 6-3. In first round clashes, Serbian ninth seed Janko Tipsarevic crashed out to Feliciano Lopez of Spain 6-7 (2-7), 6-7 (3-7), dealing a heavy blow to his hopes of reaching the ATP World Tour Finals. Austrian 14th seed Jurgen Melzer, who defeated Rafael Nadal to reach the quarterfinals in Shanghai last year, beat Croatia's Ivan Ljubicic 6-4, 6-2, and Alexandr Dolgopolov, seeded 12, beat Lukasz Kubot of Poland 6-4, 7-6 (8-6).
Japan's Kei Nishikori overcame a disastrous start against Robin Haase to defeat the Dutchman 0-6, 7-5, 7-6 (7-5).
