When Williams reached the semifinals of the event, she sewed up her return to No. 1, even though Azarenka, with a three-set win Sunday, repeated as the tournament champion.
Williams is 44-3 since last year's French Open, winning titles at Wimbledon, the Olympics, the U.S. Open and the WTA Championships along the way. That has allowed her to amass 10,590 points in the rankings while Azarenka is second with 10,325.
Monday officially marks the sixth time Williams reached the No. 1 ranking. It is her 124th week atop the rankings, which is sixth most. Monica Seles is fifth on that list with 178 weeks. At 31, Williams is the oldest woman to be ranked No. 1.
Angelique Kerber has 5,400 points, which is sixth most, and is followed by No. 7 Sara Errani (4,820) and eighth-ranked Petra Kvitova with 4,510. Samantha Stosur, with 3,835 points, remains No. 9 and Caroline Wozniacki (3,570) is 10th.
Lara Arruabarrena-Vecino won the WTA tournament in Cali, Columbia, but, due to a shift in the WTA schedule, dropped 16 places in the rakings to No. 97. The same week last year she won the WTA event in Bogota, Colombia, but she can regain those points as the Bogota tournament is this week.
The big tournament on this week's schedule, however, is in the United Arab Emirates where Azarenka and Williams head a very strong field. Only Sharapova and Li among the Top 10 players are missing the tournament.