The world tennis number one Roger Federer will face his U.S. Open conqueror Juan Martin del Potro in the round-robin stage of the ATP Tour finals after getting the rough end of the draw overnight for the season finale.
The Swiss is still not guaranteed to end the year on top of the rankings and will also face Britain's Andy Murray and Spain's Fernando Verdasco in Group A when play starts on Sunday night.
Rafael Nadal, who missed last year's event in Shanghai and has no ranking points to defend, has the easier draw as he attempts to topple Federer from the number one spot.
The Spaniard, will play Serbia's world number three and 2008 champion Novak Djokovic, Russian Nikolay Davydenko and Swede Robin Soderling, who ended Nadal's four-year reign at the French Open in May.
