Top-seeded Yulia Putintseva of Kazakhstan saved three set points in the first set and went on to defeat Mona Bathel 7-6 (8), 6-1 on Wednesday to reach the quarterfinals of the Nurnberger Versicherungscup in Germany.
Bathel, a German, trailed 0-3 on a double break in the opening set but rallied to force a tiebreaker, staving off four set points before losing the set.
Putintseva will play Germany's Anna-Lena Friedsam, a wild-card entry ranked No. 523 in the world. Friedsam, coming off shoulder surgery, cruised past eighth-seeded countrywoman Andrea Petkovic 6-3, 6-1.
Three other seeds lost: Tamara Zidansek of Slovenia upset third-seeded Ajla Tomljanovic of Australia 6-3, 6-4. Veronika Kudermetova defeated fellow Russian Ekaterina Alexandrova, the fifth seed, 6-0, 6-4. Romania's Sorana Cirstea beat No. 6 seed Kirsten Flipkens of Belgium 7-6 (6), 6-2.
No. 2 seed Katerina Siniakova of the Czech Republic rallied past Mandy Minella of Luxembourg 1-6, 6-3, 6-2.
Internationaux de Strasbourg
Second seed Aryna Sabalenka of Belarus won eight of the last 11 games to defeat Germany's Laura Siegemund 6-4, 6-3 to reach the quarterfinals on the clay courts in France.
Sabalenka, the highest-seeded player remaining in the tournament, will play Puerto Rico's Monica Puig, the 2014 winner of the event. Puig coasted past Australia's Astra Sharma 6-2, 6-2, never losing serve.
Fourth seed Caroline Garcia of France -- the 2016 champion -- finished off a rain-delayed match from Monday to beat Shelby Rogers 4-6, 6-4, 6-3, and then returned to the court to beat Sweden's Rebecca Peterson 6-2, 6-3.
Australia's Samantha Stosur -- a two-time winner (2015 and 2017) in Strasbourg -- was ousted by sixth-seeded Ukranian Dayana Yastremska 6-0, 6-2. The other two seeds in action, No. 3 Qiang Wang and No. 3 Saisai Zheng, both of China, were upset.
--Field Level Media