Samantha Stosur's hopes of ending her two-year wait for a WTA Tour title were ended by Sofia Kenin on Saturday.
Zhang Shuai, a two-time WTA Guangzhou Open champion, was upset on Thursday, but Sofia Kenin recovered to advance and Sam Stosur also won.
Marie Bouzkova claimed another notable scalp in 2019 as Elina Svitolina retired at the Guangzhou Open.
Having climbed into the WTA's top 100, Kristie Ahn caught the eye again with a swift demolition of Timea Bacsinszky in Seoul.
Both of Wang Qiang's WTA titles have come on home soil after she won the Guangzhou Open.
There will be no repeat Korea Open triumph for Jelena Ostapenko, who was beaten comfortably by Ekaterina Alexandrova on Friday.
Defending Korea Open champion Jelena Ostapenko was made to wait to play her second-round match on Thursday due to heavy rain.
Alize Cornet failed to make the most an overnight reprieve at the Guangzhou Open as Jennifer Brady reached round two.
Alize Cornet will resume her first-round match with Jennifer Brady down a set after rain forced their clash to be suspended.
Aleksandra Krunic's first WTA Tour final ended in defeat as Zhang Shuai claimed the Guangzhou Open title for the second time.