Samantha Stosur will face world No.1 Serena Williams twice in as many weeks after defeating Varvara Lepchenko in straight sets in her opening encounter the Cincinnati Masters.

Stosur overcame American qualifier Lepchenko 6-2 7-5 to advance to the second round where she’ll again meet Williams.

Williams easily dispatched the Australian 6-0 6-2 in the second round of the Toronto Masters last week.

Fellow Australian Casey Dellacqua suffered a first-round exit in Cincinnati, going down 7-6 (7-4) 6-2 to French qualifier Pauline Parmentier.

In other matches, eleventh-seeded Dominika Cibulkova became the first seeded woman to be ousted, losing to Anastasia Pavlyuchenkova, 6-3 6-3.

Ninth-seeded Ana Ivanovic came from behind in the second set to beat Sorana Cirstea, 6-1 7-5, while 12th-seeded Caroline Wozniacki dispatched Magdalena Rybarikova, 6-2 6-3, in a match that was interrupted by a late-afternoon storm and 13th-seeded Flavia Pennetta prevailed over qualifier Chanelle Scheepers, 6-3 6-7 (7-3) 6-2.

In women’s play earlier in the day, Madison Keys pulled off a 6-2, 6-4 win over Alize Cornet to advance.