According to the Associated Press, "Wimbledon champion Rafael Nadal, No. 1-ranked Roger Federer and No. 3 Novak Dkojokic have qualified for the season-ending Tennis Masters Cup... The ATP announced Wednesday that those three singles players and doubles teams Daniel Nestor and Nenad Zimonjic, and Bob and Mike Bryan clinched berths at the Nov. 9-16 tournament at Shanghai’s Qi Zhong Stadium."
Apparently, only 8 singles players and 8 doubles teams receive invites. So this is a pretty prestigious tournament then, eh?
Nadal, Federer, Djokovic qualify for Masters Cup - Tennis - Yahoo! Sports