Second-seeded Johanna Konta has withdrawn from the Charleston WTA tournament due to a shoulder injury.
The Australian-born Briton is coming off the biggest title of her 11-year career when she claimed the Miami Open, beating Caroline Wozniacki to move to world No.7.
In first-round matches Monday (Tuesday AEST), Alison Riske defeated fellow American Kayla Day 7-5 4-6 6-0.
Riske closed with a dominant third set, taking advantage of three double-faults and saving two break points.
Day converted two of 13 second serves in the decisive set on the green clay at Daniel Island.
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Elsewhere in the first round, Kateryna Bondarenko of Ukraine defeated Evgeniya Rodina of Russia 6-4 7-5; Naomi Osaka of Japan rallied past Johanna Larsson of Sweden 6-7 (4) 6-4, 6-2; Monica Puig of Puerto Rico was up 4-6 6-2 4-1 when Katerina Siniakova of the Czech Republic retired.
Also, Jelena Ostapenko of Latvia topped Ana Bogdan of Romania 6-4 6-2; Ons Jabeur of Tunisia defeated Marina Erakovic of New Zealand 6-4 6-1; and Germany's Andrea Petkovic beat Lara Arruabarrena of Spain 7-5 6-2.
