Dubai - Former world No 1 Karolina Pliskova beat Carla Suarez Navarro 5-7, 6-2, 6-4 to clinch the first of the quarter-final places at the Dubai Championships on Wednesday.
Third seed Pliskova was joined in the last eight by Japan's Naomi Osaka, a winner over Anett Kontaveit of Estonia, 6-2, 7-6 (7/5).
Pliskova, who headed the WTA rankings from mid-July to mid-September, needed a fightback to go through at the Aviation Club after losing the opening set to her 27th-ranked opponent from the Canary Islands.
The Czech won the second set and survived a run of three consecutive breaks of serve in the third, taking a 4-3 lead over Suarez Navarro.
Pliskova reached 5-3 and served out the fighting win two games later in just over two hours.
"I was not playing the best tennis today, we were both a little bit struggling," Pliskova said after finishing with 11 aces, six double-faults and losing her serve five times.
"For me, this was the first match here after couple days of practice. I haven't had that many matches for last couple of weeks since I came from Melbourne.
"I'm just finding the rhythm of the matches. Finally I got the win, so maybe it's better in the next match.
"These are the important wins - when you are not playing your best tennis."
Osaka, ranked 48th, now stands 2-0 over Kontaveit, taking victory in 90 minutes with six aces and the same number of service breaks.
Results from the WTA tournament in Dubai on Wednesday (x denotes seeding):
Naomi Osaka (JPN) bt Anett Kontaveit (EST) 6-2, 7-6 (7/5)
Karolina Pliskova (CZE x3) bt Carla Suarez Navarro (ESP) 5-7, 6-2, 6-4
Angelique Kerber (GER x6) bt Sara Errani (ITA) 6-4, 6-2