Defending champion Gilles Muller fell to a shock 6-3, 7-5 defeat by Australian qualifier Matthew Ebden in the Libema Open second round Wednesday.
World No. 69 Ebden progressed to his second ATP World Tour quarterfinals and will face Marius Copil, who secured a 7-5, 4-6, 6-4 win over Japanese No. 7 seed Yuichi Sugita.
Frenchman Muller, positioned at 32nd in the ATP rankings, followed his title win at Hertogenbosch last year with a run to the Wimbledon quarterfinals.
Australian Bernard Tomic, a Wimbledon quarterfinalist in 2011, recorded his first win against a top-50 player since last June as he beat No. 6 seed Robin Haase 6-3, 7-5 to advance to the last eight.
Tomic, ranked 181st in the world, will face fourth seed Fernando Verdasco in the next stage after the Spaniard ousted Russian Daniil Medvedev 6-4, 6-1.
In the women's draw, top seed CoCo Vandeweghe marched into the last eight with a 7-6 (4), 6-3 win over Arantxa Rus in the second round.
American Vandeweghe, a quarterfinalist at Wimbledon last year, is on course to win her third title at Hertogenbosch after a commanding performance in which she hit 26 winners, including 11 aces, to dismantle Rus's challenge in a little over 90 minutes.
World No. 16 Vandeweghe will take on the winner of the match between Alison Riske and qualifier Fanny Stollar in the last eight.
Russian Veronika Kudermetova, who stunned defending champion Anett Kontaveit in the first round, reached her first WTA quarterfinal after ousting Belinda Bencic 6-2, 2-6, 6-3.
The 21-year-old will face Aleksandra Krunic in the last eight after the No. 7 seed eased to a 7-5, 6-2 win over Bibiane Schoofs.