Roger Federer is hoping to win his 100th career title at the ATP Finals in London.
The Swiss 20-time Grand Slam champion, 37, has won the season-ending event six times.
His opponents in the Lleyton Hewitt group for the round-robin stage are Kevin Anderson, Kei Nishikori and Dominic Thiem.
The world number three starts his campaign against Nishikori on Sunday (not before 20:00 GMT).
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