World number one Novak Djokovic has been drawn against Alexander Zverev, Marin Cilic and John Isner in the group stages of the ATP Finals in London.
Djokovic is back at the top of the rankings this week for the first time in two years after Rafael Nadal was forced to withdraw from the Paris Masters through injury.
Isner, the lowest-seed in the eight-player tournament, was a late replacement for Nadal, who announced on Monday he would miss the tournament to undergo surgery on his ankle.
Roger Federer, who is seeking his 100th career title, headlines the other group.
The Swiss will face Kevin Anderson, Dominic Thiem and Kei Nishikori. Anderson came back from two sets to love down to beat the 20-time Grand Slam champion at Wimbledon in July on his way to the final.
The ATP Finals begin at London's O2 Arena on November 11.
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