Williams defeated Jankovic in Sunday's final at the China Open. It was the 10th tournament title of the year for Williams. No. 2-ranked Victoria Azarenka, the defending China Open champion, was beaten in the first round.
As a result, Williams, with 13,260 points, now has a 4,775-point lead over Azarenka. In comparison, only five players have as many as 4,700 points. Williams has held the No. 1 spot for the last 34 weeks and 157 weeks overall.
The win over Jankovic was her 56th WTA title, breaking a tie with Lindsay Davenport for fourth most championships all-time. Steffi Graf is third on that list at 107. Martina Navratilova owns the record with 167 and Chris Evert won 157 tournaments.
Jankovic fell to 0-4 in finals matches versus Williams but her performance in Beijing was enough to lift her to No. 8 in the rankings, up from 11th. Caroline Wozniacki and Angelique Kerber were each pushed down one spot to ninth and 10th, respectively.
Jankovic was to have been the top seed for the HP Open in Japan this week but withdrew due to a left hip injury. No. 14 Sabine Lisicki is the highest ranked woman in that tournament. Kerber leads the field at the Generali Ladies Linz tournament in Austria.
The WTA Top 10 listing player's name, home country and ranking points:
1. Serena Williams, United States, 13,260
2. Victoria Azarenka, Belarus, 8,485
3. Maria Sharapova, Russia, 6,941
4. Agnieszka Radwanska, Poland, 6,195
5. Li Na China, 5,365
6. Sara Errani, Italy, 4,435
7. Petra Kvitova, Czech Republic, 4,315
8. Jelena Jankovic, Serbia, 3,860
9. Caroline Wozniacki, Denmark, 3,845
10. Angelique Kerber, Germany, 3,645