Qualifier Ons Jabeur claimed the scalp of Shelby Rogers and Mandy Minella also produced an upset by beating Caroline Garcia to reach the quarter-finals of the Taiwan Open on Wednesday.
Jabeur is 133 places below seventh seed Rogers in the world rankings, but the 22-year-old Tunisian outsider is through to the last eight after winning 7-5 6-2.
The 181-ranked Jabeur fired down 11 aces and, despite going down 3-1 in the opening set, broke her opponent four times to set up a meeting with either top seed Elina Svitolina or Lucie Hradecka.
There will be no fourth WTA singles title for Garcia this week after the third seed went down 6-4 6-4 to Minella.
Five consecutive games went against serve in the second set before the unseeded Minella held to lead 5-3 and served out the match to love.
Anastasija Sevastova was another seed to bow out, with wildcard entry Lucie Safarova prevailing 6-2 6-4.
Sixth seed Misaki Doi avoided the same fate, though, as last year's runner-up defeated Japanese compatriot Risa Ozaki 6-4 6-3 on day three of the WTA International tournament.