Third-seeded Andrea Petkovic of Germany advanced to the Diamond Games semifinals Friday after beating sixth-seeded Slovakian Dominika Cibulkova 7-6 (2), 6-0 in a scrappy match featuring 11 breaks of serve.
Serena Williams saw that older sister Venus was progressing to the fourth round at a Grand Slam tournament for the first time since 2011, and it inspired her own comeback win Saturday at the Australian Open.
The Williams sisters advanced to the third round at the Australian Open, with top-ranked Serena fending off three set points before going on a 10-game roll to beat Vera Zvonareva 7-5, 6-0, and Venus beating fellow American Lauren Davis in straight sets.
Two-time champion Victoria Azarenka continued her comeback from a foot injury with a convincing 6-3, 6-2 win over Sloane Stephens on Tuesday and next will have to play US Open finalist Caroline Wozniacki, who beat 18-year-old Taylor Townsend 7-6 (1), 6-2.
Fifth-seeded Ana Ivanovic struggled with her serve and lost in three sets to Czech qualifier Lucie Hradecka in first big upset of the Australian Open on Monday, Ivanovic's worst result in a major since 2011.
The US Open's young upset artist finished 2014 as the No. 1 junior and says she's got her game back in order. Still, the 15-year-old is skipping the Australian Open this month and mulling her timetable for turning pro.