Nadal has never won the ATP World Tour Finals while Federer has on six occasions , with four of those coming indoors -- Houston in 2003 and 2004 proving the exception . Tennis legends disagree on nature of ATP World Tour Finals . The top 10 players in the world are ranked according to their performance at this year's event -- which begins June 1 and ends July 31. 2013 action got underway on Monday as Stanislas Wawrinka beat Tomas Berdych . Juan Martin del Potro rallied to beat Richarg Gasquet in the evening session .
Tennis legends disagree on nature of ATP World Tour Finals . The top 10 players in the world are ranked according to their performance at this year's event -- which begins June 1 and ends July 31. 2013 action got underway on Monday as Stanislas Wawrinka beat Tomas Berdych . Juan Martin del Potro rallied to beat Richarg Gasquet in the evening session .