With 54 WTA titles since winning her first championship in February 1999, Williams is ninth on the all-time list for most tournament titles. She would move into a tie for seventh with Lindsay Davenport and Virginia Wade with her next title.
Since Williams didn't enter the 2012 Rogers Cup, she nets 900 rankings points this week, giving her a massive 3,115-point lead over second-ranked Victoria Azarenka in the world rankings.
Petra Kvitova was the defending Rogers Cup champion but fell in the quarterfinals to Cirstea, a result that drops her two rankings places from seventh to No. 9. Marion Bartoli, now seventh, and Angelique Kerber, the new No. 8, each move up one place.
Cirstea knocked off three Top 10 players en route to the finals against Williams. The runner-up finish in Toronto boosts her six spots to No. 21.
Shahar Peer beat Zheng Shuai in the WTA's 125K series tournament final in Suzhou, China. Peer improves 30 spots to 83rd in the rankings and Zheng leaps 44 places to 151st.
All of the WTA's Top 10 players are in the field for this week's Western and Southern Open in Cincinnati. No. 5-ranked Li Na won the event last year, beating Kerber in the final.
The women's world tennis rankings listing player's name, home country and ranking points:
1. Serena Williams, United States, 11,920
2. Victoria Azarenka, Belarus, 8,805
3. Maria Sharapova, Russia, 8,765
4. Agnieszka Radwanska, Poland, 6,335
5. Li Na, China, 5,330
6. Sara Errani, Italy, 5,125
7. Marion Bartoli, France, 4,365
8. Angelique Kerber, Germany, 3,915
9. Petra Kvitova, Czech Republic, 3,710
10. Caroline Wozniacki, Denmark, 3,465