Clijsters overcame 98-degree temperatures to beat three-time champion Lindsay Davenport, 6-1, 3-6, 6-1, in the final of the JP Morgan Chase Open.
By capturing her WTA Tour-leading sixth title in 11 finals this year, Clijsters will jump 45 points past an injured Williams when the rankings are released on Monday.Williams underwent left knee surgery Aug. l, which will keep the defending U.S. Open champion sidelined 4-6 weeks.
The 20-year-old Belgian becomes the 12th player to hold the top spot since the rankings began in 1975 -- and the first to do it without a Grand Slam title.
Davenport once was the world No. 1 player and has captured 38 tournaments, including three Grand Slam crowns, but failed to win her second title in the last 22 months.