With the US Open less than a fortnight away, players are using the hard-court event as a vital tune-up to the year's final major in New York.
However, there was no joy for the Australian trio of Daria Kasatkina, Ajla Tomljanovic and Kimberly Birrell, who all lost their second-round matches in Cincinnati on Sunday (local time).
Kasatkina couldn't live up to her 15th seeding, falling to talented Italian Lucia Bronzetti in three sets.
The Australian fought back after a disappointing opening set to handily win the second, before Bronzetti triumphed 6-3 1-6 6-4.
Veteran Tomljanovic pushed 16th seed Clara Tauson to the brink, before the Dane clinched victory 6-3 6-7 (5-7) 6-4.
In a battle of the big servers, the tall Dane blasted down 14 aces to nine for the Australian.
Tomljanovic was only able to convert one of the five break points she set up, while Tauson managed to break three times from four opportunities.
Tauson's victory continues a great fortnight after she beat major winners Iga Swiatek and Madison Keys on her way to the semi-finals of last week's Canadian Open.
Birrell gave a good account of herself but was unable to stop the march of fourth-seeded American Jessica Pegula, last year's finalist winning 6-4 6-3.
Australia's hopes in the women's section of the tournament now rest with talented teen Maya Joint.
The young Aussie upset 18th-seeded Brazilian Beatriz Haddad Maia in her second-round match on Saturday to set up a meeting with 12-seeded Russian Ekaterina Alexandrova.
In other action on Sunday, second-seeded American Coco Gauff, the  2023 champion, overcame early problems on serve to cruise past China's Wang Xinyu 6-3 6-2.
Seventh seed Jasmine Paolini, of Italy, edged into the next round with a tight 7-6 (7-2) 7-6 (7-5) victory over Maria Sakkari, of Greece.
However, eighth-seeded American Emma Navarro suffered a surprise loss, with Germany's Ella Seidel beating her 6-4 1-6 6-4.
- with Agencies
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