Samantha Stosur defeated both second-seeded Agnieszka Radwanska and No. 1-seeded Azarenka at the Southern California Open en route to her fourth WTA title. The 6-2, 6-3 win over Azarenka in Sunday's final was the first time in nine career meetings she has defeated Azarenka.
But Azarenka, by advancing to the final, had secured enough rankings points to move up one spot in the rankings. Her move forces Sharapova to third by 30 points in the rankings.
The Azarenka-Sharapova flip was the only change this week in the Top 10 although Stosur pulled to within 250 points of No. 10-ranked Caroline Wozniacki. Stosur was 13th last week and is now 11th in the rankings.
Magdalena Rybarikova defended her Citi Open title in Washington Sunday, beating Andrea Petkovic. That boosts her ranking one place to No. 42. Petkovic jumps 14 spots to 50th.
All of the WTA's Top 10 players, except Azarenka and Sharapova, are in the field for this week's Rogers Cup tournament in Toronto. Williams is the top seed and defending champion Petra Kvitova is seeded sixth.
Azarenka withdrew from the tournament citing a lower back injury. Sharapova pulled out of the Rogers Cup last week due to a hip injury.
The WTA Top 10 with player's name, home country and ranking points:
1. Serena Williams, United States, 11,245
2. Victoria Azarenka, Belarus, 8,805
3. Maria Sharapova, Russia, 8,765
4. Agnieszka Radwanska, Poland, 6,165
5. Li Na, China, 5,555
6. Sara Errani, Italy, 5,100
7. Petra Kvitova, Czech Republic, 4,385
8. Marion Bartoli, France, 4,365
9. Angelique Kerber, Germany, 3,920
10. Caroline Wozniacki, Denmark, 3,660