Novak Djokovic has warned a resurgent Rafael Nadal that he is in no mood to relinquish his world No 1 ranking without a fight.
The pair headline the men's draw at the ATP China Open and defending champion Djokovic has vowed to hold onto his title in Beijing.
However, Nadal is just 260 ranking points behind the Serb and could replace him for the first time since July 2011 with a good week.
The Spaniard has been in sensational form since returning from a seven-month injury break, winning 10 titles - including a record eighth French Open crown before he beat Djokovic in the final of the US Open earlier this month.
Djokovic acknowledged that the current world No 2 has had a more consistent season, but is confident he can reproduce the form which has seen him unbeaten in three visits to the Chinese capital, following wins in 2009, 2010 and last year when he beat Jo-Wilfried Tsonga.
"As long as there is a chance, I will fight for that top spot," said the six-time Grand Slam champion.
"But, again, with no doubt he has the best results this year. This year he's been the best player in the world. I have been having ups and downs throughout this year. But still it was a quite good season for me, but it's not over.
"I want to focus on this week's China Open because this is where I traditionally play well, and I would like to have another successful week."
Reigning champion Djokovic will play Czech Lukas Rosol, who is ranked 46th in the world, in his opening game, while Nadal will face a qualifier who is yet to be named.