The 35-year-old Tammy is the last Thai remaining in the tournament after Luksika Kumkhum was ousted by fourth-seeded Taiwanese Kai-Chen Chang 6-4 4-6 1-6 in the opening round.
Tammy’s last-four place came courtesy of wins against Tarina Diyas of Kazakhstan 6-3 6-4 in the first round and Irena Pavlovic of France 6-3 4-6 6-1 in the second round.
Elsewhere, in the US$10,000 Vietnam F4 Futures, rising Thai star Wishhaya Trongcharoenchaikul moved into the quarter-finals with a 6-3 6-4 win over Chinese Bowen Ouyang. He next takes on Japanese third-seeded Hiroyasu Ehara.