Playing in her first tournament in more than six months, Kuznetsova, 33, passed her second two-hour test on Lugano's clay courts. Kuznetsova, ranked No. 109, got the key break early in the third set against Bacsinszky, another injury-hit former top-10 player now ranked No. 112.
Two more seeded players lost Thursday, leaving eighth-seeded Vera Lapko as the only one left in the quarterfinals. Lapko won 6-2, 6-0 against Evgeniya Rodina, while third-seeded Viktoria Kuzmova was beaten 6-3, 3-6, 6-2 by Iga Swiatek, the Wimbledon junior champion.
Seventh-seeded Rebecca Peterson lost 1-6, 6-4, 7-6 (2) to Veronika Kudermetova.
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