Williams had her play severely cut back by a series of injuries since she won at Wimbledon in 2010 and her ranking, which was No. 1 three months after the Wimbledon win, suffered.
But she's 10-2 in matches this year and has moved back to No. 10, pushing Andrea Petkovic from 10th to No. 11.
Victoria Azarenka, who had her first loss of the year in the quarterfinals in Miami is No. 1 for a 10th consecutive week. She has 8,980 rankings points, solidly ahead of No. 2 Maria Sharapova, who has 7,930 points after her third runner-up finish of the year.
Petra Kvitova is third with 7,095 and Agnieszka Radwanska, who beat Sharapova in the Sony Ericsson finals, is fourth with 6,710.
Samantha Stosur is fifth at 5,825 points while Caroline Wozniacki (5,720) comes sixth. Marion Bartoli -- the only player to beat Azarenka this year -- is seventh with 5,020 points and Li Na (4,880) is eighth.
Vera Zvonareva (3,895) is ninth but only 65 points ahead of Williams.
Williams is among four Top 10 players in the draw for this week's Family Circle Cup. Radwanska was to have been seeded No. 1 in the event but withdrew because of a back problem. Wozniacki, the defending champion, is also missing the tournament.
Stosur, Bartoli and Zvonareva join Williams in the draw