He needs to win just two matches in London to clinch the No. 1 spot while Djokovic must win the tournament to have a chance.
"I had a sensational season and I would not (trade) all the emotions I went through (for) being the No. 1,'' Nadal said ahead of his first round robin match against fellow Spaniard David Ferrer on Tuesday.
The London tournament, which brings together the eight best players of the season, is the only major title still missing from Nadal's collection of trophies.
Nadal qualified for the event for the ninth straight year but his best result in the event is a runner-up finish in 2010.
Drinking a milk-shake and smiling at the start of his news conference, Nadal's mood darkened when he was asked about his failure to win the indoor tournament.
"We qualify by playing on all surfaces, but the tour finals are always on hard courts,'' said Nadal, suggesting that the ATP should rotate the surface to give players an equal chance of winning. "One of the small reasons (I did not win) was fatigue, one of the main reasons was I have never been a fantastic player on the indoor surface. Also I have been unlucky. The tour finals have been indoors from 2005 until now, so I am a bit unlucky with this. For me it is more fair to have it outdoors on different surfaces.''
But Nadal, widely considered the best clay-court player in the history of the game, doesn't expect to see the event played on another surface before the end of his career.
"I say it for the next generation and because it would be interesting for the fans,'' he said. "This is a great place to play, I have never been to a tournament with a better atmosphere, but that doesn't mean the ATP can't be a little bit more fair with the players.''
- AP