Tunisian second seed Ons Jabeur is into the Birmingham Classic quarter-finals after beating Canada's Leylah Fernandez 6-4 3-6 7-6 (7-3).
Jabeur, 26, took the first set comfortably against her 18-year-old opponent and although Fernandez levelled the match, Jabeur won the decider in a dominant tie-break.
She is the highest-ranked Arab in WTA history and the African number one.
"I hope I can inspire a new generation to come and help me," she said.
In the last eight she faces Russia's Anastasia Potapova, the 2016 Wimbledon Girls' champion, who beat France's Kristina Mladenovic 6-3 6-3.
Latvia's fifth seed Jelena Ostapenko was denied a third successive appearance in the quarter-finals, losing a heavy-hitting contest 7-6 (7-4) 4-6 6-2 to Czech qualifier Tereza Martincova.
Fourth seed Daria Kasatkina from Russia ended the day's play by booking the last quarter-final berth with a 6-2 7-5 win over 18-year-old Ukrainian Marta Kostyuk, and will face Martincova.
Britain's Heather Watson, who went through on Wednesday after Nottingham Open finalist Zhang Shuai retired injured during the first set of their match, will face Donna Vekic on Friday.
In Berlin, fifth seed Belinda Bencic was joined by two-time Grand Slam champions Victoria Azarenka and Garbine Muguruza in the quarter-finals.