Updated

Former U.S. Open champion Samantha Stosur posted a first-round victory Monday at the $795,000 Southern California Open tennis event.

The fifth-seeded Australian handled American Varvara Lepchenko 7-5, 6-1 on the hardcourts at La Costa Resort and Spa.

Sixth-seeded Serbian Jelena Jankovic also prevailed, while 2010 champ Svetlana Kuznetsova was ousted. Jankovic battled back to fend off American Mallory Burdette, 4-6, 6-1, 6-4. Kuznetsova dropped a 6-2, 6-4 decision to French wild card Virginie Razzano.

This week's top seed is 2013 Australian Open champion and 2012 U.S. Open runner-up Victoria Azarenka. Her second-round opponent will be Francesca Schiavone, a 7-6 (7-4), 6-7 (6-8), 6-4 winner over fellow Italian Flavia Pennetta.

American Bethanie Mattek-Sands also advanced with a 2-6, 6-1, 6-2 victory over Puerto Rico's Monica Puig.

Slovakian Dominika Cibulkova, fresh off her title last week in Stanford, topped reigning Wimbledon champ Marion Bartoli in last year's Carlsbad finale.

This week's winner will claim $125,000.