MASON, Ohio -- Donna Vekic was defeated in her first match since winning the silver medal in the Olympics, falling to Ashlyn Krueger 5-7, 7-6 (4), 6-2 on Tuesday at the Cincinnati Open.
Krueger played her win into the field through the qualifying rounds, where she defeated Naomi Osaka. The American then opened her first appearance in the main draw in Cincinnati by knocking off Vekic, the No. 16 seed from Croatia who lost to Qinwen Zheng in the women's gold medal match in Paris.
On the men's side, Brandon Nakashima upset No. 11 seed Taylor Fritz 6-4, 4-6, 7-6 (4), while No. 12 Ben Shelton edged Reilly Opelka 7-6 (3), 7-6 (3) in another All-American matchup.
Shelton, Nakashima and Krueger were among five Americans who advanced Tuesday in the hard-court tune-up for the US Open. Alex Michelsen and Frances Tiafoe also moved on.
The only other seeded competitor to advance in men's action was No. 14 Lorenzo Musetti of Italy, the bronze medalist in Paris who outlasted Chile's Nicolas Jarry 4-6, 7-6 (5), 7-6 (4).
Ninth-seeded Daria Kasatkina and No. 15 Marta Kostyuk were the women's seeded winners.
Both No. 1 seeds play their opening matches Wednesday. Jannik Sinner of Italy takes on Michelsen in the afternoon, while Iga Swiatek faces Varvara Gracheva in a night match.