Second-seeded Johanna Konta has withdrawn from the Volvo Car Open because of a sore shoulder.
The Australian-born Briton is coming off the biggest title of her 11-year career. She beat Caroline Wozniacki in the Miami Open final Saturday to move to No. 7 in the rankings.
In first-round matches Monday, 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 just two of 13 second serves in the decisive set on the green clay at Daniel Island.
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.