Both players are in action in the China Open next week and a good tournament for the Spaniard could see him move to the top of the pile.
"It will be very tough to become number one," Nadal told reporters. "But if I am still playing the same way I did the last couple of months, I hope to have my chance here or in the next few weeks."
Nadal has not topped the world rankings since 2011. Djokovic is the tournament's defending champion and will face Lukas Rosol in his first match.