Magdalena Rybarikova's Wimbledon preparations suffered a blow as the Slovakian was ousted by unseeded German Mona Barthel in the second round of the Nature Valley Open in Nottingham on Wednesday.
Rybarikova, 29, a semifinalist at Wimbledon last year, fell to a shock 6-3, 6-1, 7-5 defeat by Barthel, who will face either defending champion Donna Vekic or Vera Lapko in the quarterfinals.
No. 3 seed Naomi Osaka recorded a dominant 6-3, 6-2 win over Czech Republic's Denisa Allertova in just over an hour to reach her first WTA quarterfinal on grass, where she will take on rising Romanian Mihaela Buzarnescu.
Buzarnescu had her best Grand Slam run at the French Open, where she reached the last 16, and continued her good form by beating Irina Falconi 6-3, 5-7, 6-3 in the second round.
Dalila Jakupovic strolled to a 6-4, 6-3 win over Magdalena Frech to book a quarterfinal berth against the winner of the all-British showdown between Johanna Konta and Heather Watson, which will be played Thursday.
Australian top seed Ashleigh Barty will also be in action Thursday as she battles for a quarterfinal place against China's Yin Duan.