Unseeded American Shenay Perry upset 15th-seeded Barbora Zahlavova Strycovia of the Czech Republic 7-5, 6-1 on the green clay at the Family Circle Tennis Center.
Viktoriya Kutuzova also won in straight sets, defeating fellow Ukrainian Mariya Koryttseva 6-1,6-1. Sabine Lisicki of Germany defeated Marie-Eve Pelletier of Canada 7-5, 6-4, and Stephanie Dubois of Canada defeated Katie O'Brien of Britain 4-6, 6-2, 6-1.
Top-seeded Elena Dementieva, ranked No. 3, will face American Julie Ditty in the late match Tuesday.
Defending champion Serena Williams withdrew after sustaining a leg injury in Miami earlier this month.
Perry, Kutuzova advance at Family Circle Cup