The duo are in action at the China Open next week and a good tournament for the Spaniard could see him replace Djokovic at the top for the first time since 2011.
Djokovic admits that Nadal has been the best player this year after 10 title wins including the French Open and US Open.
"As long as there is a chance, I will fight for top spot," Djokovic told reporters. "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 the year, but still was quite a good season.
"I want to focus on this week's China Open because this is where I traditionally play well."
Djokovic is the tournament's defending champion and will face Lukas Rosol in his first match.