Top seed Hsu Ya Ching of Taipei set up a quarter-final clash with Indonesia's Fitriani at the Vietnam Open on Thursday.
Hsu needed just 33 minutes to defeat another Indonesian, Dinar Dyah Ayustine, 21-15, 21-12, while fifth seede Fitriani advanced with a 21-14, 21-16 victory over Japanense qualifier Natsuki Nidaira.
Also advancing was third seed Cheung Ngan Yi of Hong Kong, who had far too much firepower for local player Nguyen Thuy Linh, wrapping up a 21-5, 21-13 result in 35 minutes.
Malaysian qualifier Soniia Su Ya Cheah was a surprise 21-9, 21-18 winner over countrywoman Yin Fun Lim. She moves on to face Vietnamese fourth seed Vu Thi Trang, who defeated Yulia Yosephin Susanto 21-18, 16-21, 21-14.
Others to book their spots in the last eight included Singapore's Yeo Jia Min and Chiang Mei Hui of Taipei.