Novak Djokovic poses with the trophy after defeating Rafael Nadal in Beijing on Sunday.

AFP/Beijing

Novak Djokovic crushed his age-old rival Rafael Nadal 6-2, 6-2 on Sunday to seal his sixth China Open title and extend his amazing unbeaten run at the Beijing tournament.

The world number one underlined his superiority in men's tennis as he thrashed a fading Nadal for his 29th win at an event he also won in 2009, 2010, 2012, 2013 and 2014.

Djokovic won three of the four Grand Slam finals this year and he shows no signs of slowing down at the end of the season, after losing only 18 games in his romp to the Chinese title.

The Serb, who has never lost a final in China, has also three Shanghai Masters titles to his name and he momentarily tripped himself up as he thanked the Beijing crowd.

"This definitely has been the most successful tournament in my career. I've won the Australian Open but Shanghai - sorry, Beijing - has been a lucky place for me," stumbled the Serb.

"I played a great match, great tournament overall and I continued playing well today," he added.

Djokovic put Nadal under pressure from the start with a thunderous opening rally, which the Spaniard lost, and the world number eight then shanked a forehand high into the air to give up the first break point.

Nadal had break points in the sixth game but Djokovic held firm, and the Serb gained his second break in the seventh game when his Spanish opponent volleyed into the net with the court at his mercy.

Nadal called the trainer early in the second set for treatment to his right foot, and when Djokovic broke to go 2-1 ahead the 14-time Grand Slam winner's challenge looked shot.

An instinctive lob over the stranded Nadal put Djokovic on his way to a second break and 4-1 lead, and after passing up two match points at 5-2, he finally sealed it with an ace for his rapturous Chinese fans.

In the longest rivalry in men's tennis history, Djokovic moves to 22 won, 23 lost - but with seven victories out of their last eight meetings, including this year's French Open quarter-finals.

With his 29th victory at the China Open, 10-time Slam champion Djokovic is also closing on Nadal's record for winning starts to a tournament after he racked up 31 before his first defeat at the French Open.

"He's having one of the most incredible seasons in the history of our sport, so congrats to him," Nadal said. "For me it's been a very positive week, I've been improving every single match."