World number nine Kei Nishikori is appearing at the ATP Finals in London for a fourth time.
The Japanese player, who has won 11 singles titles, will be hoping for a first title of 2018 at the season-ending event.
The 28-year-old's opponents in the Lleyton Hewitt group for the round-robin stage are Roger Federer, Kevin Anderson and Dominic Thiem.
He begins his campaign against Federer on Sunday (not before 20:00 GMT).
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