(AP) Defending champion Novak Djokovic and last year's runner-up Roger Federer have been placed in the same group at next week's ATP finals in London.
Djokovic also won the title in 2008, while Federer has won it a record six times.
The pair will be playing in a tough Group B that also includes Juan Martin del Potro and Richard Gasquet.
Top-ranked Rafael Nadal was placed in Group A in Saturday's draw, alongside fellow Spaniard David Ferrer, Tomas Berdych and Stanislas Wawrinka.
The season-ending tournament has a round robin format, with the eight best players divided into two groups of four. The top two finishers in each group reach the semifinals.
Wimbledon champion Andy Murray won't compete because he's recovering from back surgery.