Djokovic overcame Spain’s Rafael Nadal in straight sets and maintain a remarkable 100 percent record in the Beijing tournament, while Williams claimed a 6-2, 6-2 victory over Serbia’s Jelena Jankovic as her dominant season continues.
Djokovic, who has won the event the four times he has entered, was at his ruthless best to defeat Nadal 6-3, 6-4, a day before he is set to be unseated at the top of the world rankings by the Spaniard.
It was Nadal’s first hard court loss of the season.
The second seed in Beijing showed only rare glimpses of the form that has seen him win 10 titles this year, with his Serbian opponent racing to a 3-0 lead in the first ten minutes.
Top seed Djokovic then powered ahead, showing formidable power-hitting to take the first set 25 minutes later.
The pair displayed incredible movement in the opening game of the second set, engaging in quickfire net-play much to the delight of the crowd.
Nadal came out on top of that duel, winning the point, but Djokovic took the game to break serve.
Djokovic then kept his nerve, holding serve until the end of the match on one hour 27 minutes.
The victory was a consolation for Djokovic, who is spending his 101st week at number one. But his current streak of 48 weeks will end on Monday when the ATP announces its new rankings with Nadal at the top.
The Spaniard only needed to make the final to unseat him.
After the match, Djokovic congratulated Nadal on his achievement.
“I have to say congratulations to Rafael because he deserves definitely to be number one of the world this year with the season that he has had,” he said in an interview on court.
“He is the best player so far in 2013, there is no question about it.
“I am just very happy to be able to continue to play well and hopefully I can maintain the rhythm.”
Djokovic was in dominant form at the China Open, where he has an unbeaten run stretching back to 2009. He did not attend in 2011.
But Nadal has had the beating of Djokovic this season, coming out on top at the semi-finals at Roland Garros and last month’s final at the US Open, as well as the Canada Masters.
However he said Djokovic was “too strong” for him in Beijing at the serve. Nadal did not break his opponent throughout the match.
“I didn’t play my best match this afternoon. But he played at a greater level with his serve. I was not able to have any chance when I was returning during the whole match,” the Spaniard said.
“He was able to hit all the balls where he wanted to hit them, so when that is happening against a player like Novak you are dead.”
Nadal’s return to the top for the first time since July 2011 marks an astonishing comeback for the 13-times Grand Slam champion, who spent the second half of last year on the sidelines injured.
Heading into the match at Beijing’s National Tennis Centre, the pair had played each other 37 times, with Nadal leading the rivalry 22-15.
In the women’s tournament, Williams won her tenth title of the year with a convincing victory over world number 11 Jankovic.
The Serb only briefly threatened her opponent, breaking the American’s serve in the third game of the second set.
But any hope she had was quickly extinguished by the top seed in Beijing, who won the set’s remaining games.
The 32-year-old power hitter has already secured the year-end world number one ranking, and last month became the first woman to surpass $9 million in prize money in a single season.
Williams last claimed the China Open in 2004, while Jankovic won the tournament in 2008.