Britain's Andy Murray will play U.S. Open champion Juan Martin del Potro in the opening Group A round-robin match of the ATP World Tennis Tour finals this weekend.
World number one Roger Federer, who lost to Argentine Del Potro in the U.S. final at Flushing Meadows in September, meets Spain's Fernando Verdasco in the day's second game at London's O2 Arena.
Spain's Rafael Nadal begins his campaign in Group B against Robin Soderling, the Swede who ended his four-year reign at the French Open in May.
Soderling, beaten in the Roland Garros final by Federer, has replaced American Andy Roddick who withdrew from the event with a knee injury.
Serbian Novak Djokovic, the world number three who won the Tour title in Shanghai last year, plays Russian Nikolay Davydenko in the world's biggest indoor tennis event.
2.3 million dollars is up for grabs if a player wins the title undefeated, more than the 1.9 million Federer collected for winning his sixth Wimbledon crown this year.
