Sharapova defeated Li Na in a Top Five championship match Sunday in the Porsche Tennis Grand Prix in Stuttgart, Germany. It was a repeat of her 2012 title at the event and was her fifth title in the last year, a string that includes the 2012 French Open.
Williams leads the rankings with 11,115 points while Sharapova has 10,240 for No. 2. Victoria Azarenka slipped to 9,130 points but is still a solid third.
Agnieszka Radwanska is fourth with 6,845 points but Sunday's runner-up finish allowed Li, who has 6,000, to pull closer.
Angelique Kerber sits in sixth with 5,420 points while Sara Errani (5,350) is seventh and Petra Kvitova (5,225) comes in eighth. Samantha Stosur is ninth with 3,790 points, 30 more than No. 10-ranked Caroline Wozniacki.
Sunday's other WTA title, the Morocco Grand Prix, went to former Top 10 player Francesca Schiavone, who improved to 37th from 48th last week with her sixth WTA championship.
None of the Top 10 is entered into this week's Portugal Open where No. 14 Marion Bartoli is the top seed.