World number four Simona Halep was a big-name casualty in Wednesday's Shenzhen Open action, losing in three sets to Katerina Siniakova.
Halep, the champion in Shenzhen in 2015, had got her season under way with a three-set win over former world number one Jelena Jankovic.
But the second seed came undone on Wednesday, going down 6-3 4-6 7-5 to Siniakova - who picked up the first top-10 victory of her career.
Nina Stojanovic is Siniakova's quarter-final opponent after the Serbian qualifier beat Ons Jabeur 4-6 6-3 6-3.
With Halep's elimination, the bottom half of the draw could now open up for either Johanna Konta or Karolina Pliskova, who booked a quarter-final against the Briton with a 6-1 6-2 thrashing of Chang Kai-chen of Chinese Taipei.
Camila Giorgi beat Chinese number four Zheng Saisai 6-7 (5-7) 7-5 6-4 to book a last-eight meeting with the host nation's second-highest ranked player Wang Qiang.