London - Rafael Nadal has called on ATP chiefs to be fairer to their star players by providing a different surface each year for their flagship World Tour Finals.
World number one Nadal is unhappy that the prestigious season-ending event has been staged indoors on hard courts for the last nine years, with the tournament held in Shanghai and then at London's O2 Arena since 2009.
The Spaniard believes that is unfair to players who don't thrive indoors but have already proved the class by qualifying for the eight-man competition by succeeding on a variety of surfaces throughout the year.
Speaking on Monday a pre-tournament press conference before his Tour Finals opener against compatriot David Ferrer on Tuesday, Nadal suggested playing the tournament outdoors on a different surface each year, giving clay, grass and hard court specialists at least one good chance to win every few years.
Asked why he has never prospered in the Tour Finals, the 13-time Grand Slam champion said: "It is not only fatigue. One of the small reasons 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.
"In this tournament we qualify by playing on all surfaces, but the Tour Finals are always on hard courts."
Nadal insists he has no problems with the standard of the facilities in London or the quality of the tournament as a whole.
Still, it clearly grates on him that he has never won the Tour Finals, reaching the final just once in 2010 when he was defeated by six-time champion Roger Federer, whose game is far more suited to the quicker indoor conditions.
Given that the Tour Finals has been staged on either hard courts or carpet for all but one of its 43 editions, Nadal's wish may never be granted.
It has never been played on clay -- eight-time French Open champion Nadal's preferred surface -- and with the O2 Arena contracted to host the Tour Finals until at least 2015, there is no chance of any immediate change to an event which was last staged outdoors in Houston in 2004.
"I know it won't happen in my generation. It's not for me. I say it for the next generation and because it would be interesting for the fans," Nadal 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.
"We could change every year to play it on the surfaces we qualify for the Finals.
"That means, for example, a good clay-court player would have the chance to play on his best surface."
While Nadal wants the Tour Finals surface changed, defending champion Novak Djokovic believes a switch in venues after 2015 is also important to keep the tournament fresh.
World number two Djokovic has won the Tour Finals twice -- once each in Shanghai and London -- and he thinks it should have a new host city every three years.
"I think this tournament should definitely be organised at different places more often. Not to be held in one city for more than three years. This is my opinion," Djokovic said.
"It is in the ATP's hands, obviously, to think about this kind of thinking that I have, and I know various players share the same opinion, because of the promotion of tennis, popularising the sport in a place where maybe tennis isn't as popular.
"If we are looking to expand the consciousness about our sport, then we should look into that."