LONDON (AP) -- Despite all his success this year, Rafael Nadal still hasn't sewn up the year-end No. 1 ranking. At this stage of his career, though, that hardly matters.
After coming back from a career-threatening knee injury to win 10 titles this year, including two Grand Slams, Nadal has clearly exceeded expectations. He overtook Novak Djokovic for the No. 1 ranking last month, although the Serb can reclaim it this week at the season-ending ATP World Tour Finals.
''I've already finished the year as the world No. 1,'' said Nadal, who finished on top in 2008 and 2010. ''If it happens again, it will be perfect, but the story of my season is not the No. 1 spot. The story is that I was able to come back, to win and to be competitive again in a short spell of time.''
Since returning from a left knee injury that sidelined him for seven months, the 27-year-old Spaniard has reached the final of 13 of the 15 tournaments he's played this season, winning the French Open and U.S. Open along the way.
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,'' said Nadal, who plays his first round-robin match against fellow Spaniard David Ferrer on Tuesday.
The tournament features the eight best players of the season and is the only significant title missing from Nadal's resume. He qualified for the event for the ninth straight year but his best result is second place 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 this 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 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.''
Djokovic, the defending champion in London, did not mention a change of surface but agreed with Nadal on the idea of a venue change. The tournament moved to London in 2009, and the contract between the organizers and the ATP expires in 2015.
''I think this tournament should definitely be organized at different places more often,'' Djokovic said. ''Not to be held in one city for more than three years. This is my opinion.''