Djokovic, No. 2 since Federer won the Wimbledon Championships in July, won the China Open on Sunday. It was his 32nd ATP title overall and fourth this year.
Federer has 11,805 ranking points while Djokovic comes in with 10,970. ATP calculations indicate that if Djokovic wins this week's Shanghai Rolex Masters and Federer fails to reach the quarterfinals, Djokovic would again be No. 1 in men's tennis.
Federer has been on top of the rankings for a record 299 weeks overall. With the 300-week milestone in sight, it should be remembered that Federer pulled within one week of Pete Sampras' record of 286 weeks as No. 1 but was supplanted by Rafael Nadal. It took Federer two years to get that record.
Djokovic beat Jo-Wilfried Tsonga for the China Open title but that runner-up finish was enough to boost Tsonga one spot to No. 6. Tomas Berdych slips to seventh. Those are the only changes in the Top 10 this week.
Andy Murray, a two-time defending champ at Shanghai, is third in the rankings with 8,090 points and Nadal (7,085) is fourth, followed by David Ferrer at 5,960. Tsonga has 4,640 points, 90 more than Berdych.
In the ATP's other tournament last week, Kei Nishikori became the first Japanese player to win the Rakuten Japan Open in Tokyo. Nishikori improved his ranking to career-high No. 15.