Unseeded American Kristie Ahn has dumped sixth seed Tatjana Maria out of the Seoul Open in straight sets.
Ahn, 25, beat the world No. 54 7-5, 7-5 to advance to the last 16.
Elsewhere, Richel Hogenkamp progressed to her first WTA quarterfinal in over four years, thanks to a 6-4, 6-4 victory over Denisa Allertová.
Fifth seed Irina-Camelia Begu exited the tournament after a 6-4, 3-6, 6-2 loss to Beatriz Haddad Maia.