Serena Williams strengthens hold on No. 1 ranking

DAYTONA BEACH, Fla., April 1 (UPI) -- Serena Williams' win at the Sony Open in Miami, her ninth WTA title in the past year, tightened her hold on the No. 1 ranking in women's tennis.

Williams heads to Charleston, S.C., this week to defend her title at the Family Circle Cup. It was that tournament a year ago that turned out to be the springboard that helped propel her back to the No. 1 ranking.

Starting with Charleston last year, Williams is 67-6 with nine tournament titles, including a win Saturday over Maria Sharapova in the final at Miami. That marked her 48th WTA championship, which is sixth most all-time. She's been No. 1 for 130 weeks, which is also sixth on the all-time list.

Williams has 11,115 rankings points while Sharapova sits in second with 10,015. Victoria Azarenka is third with 9,325 and Agnieszka Radwanska, who lost to Williams in the semifinals in Miami, comes in fourth with 6,845.

Li Na remains in the No. 5 spot in the rankings with 5,880 points, followed by the tightly bunched group of sixth-ranked Angelique Kerber (5,475), No. 7 Sara Errani (5,405) and eighth-ranked Petra Kvitova (5,225).

Samantha Stosur (3,865) moves past Caroline Wozniacki (3,706) and into the ninth place in the rankings, relegating Wozniacki to 10th.

Wozniacki is the No. 2 seed behind Williams at Charleston this week but Stosur is also in the field. Kerber, the only other Top 10 player on the court this week, is the top seed at the Monterrey Open in Mexico.