World No 1 Rafael Nadal faces David Goffin in his opening ATP Finals match on Monday, while No 2 Roger Federer takes on Jack Sock.
Nadal has been drawn in the Pete Sampras group alongside Belgium’s Goffin, Dominic Thiem of Austria and Bulgarian Grigor Dimitrov.
Federer is in the Boris Becker group together with American Sock, Croatia’s Marin Cilic and Alexander Zverev of Germany.
Ready? ? pic.twitter.com/rfJbOuonTt
— Roger Federer (@rogerfederer) 8 November 2017
ATP World Tour Finals singles draw
Pete Sampras group
Rafael Nadal 
Dominic Thiem 
Grigor Dimitrov 
David Goffin 
Boris Becker group
Roger Federer 
Alexander Zverev 
Marin Cilic 
Jack Sock 
The action starts with the Boris Becker Group on Sunday, with Federer playing Sock and Zverev taking on Cilic.
The season-ending ATP finale features the eight singles players and doubles teams who have fared best and accumulated the most points during the season.
Each player competes in three matches in their group, playing for a spot in the semi-finals.
The #NittoATPFinals draw is done… and so are the Finalists' dressing room doors ☑️
— ATP World Tour (@ATPWorldTour) 8 November 2017
Nadal has already sewn up the World No 1 spot for the year, although he and Federer will be eager to claim season-ending bragging rights.
Injured trio Novak Djokovic, Andy Murray and Stan Wawrinka remain on the sidelines and and are notable absences this year.