Nadal drawn with Thiem, Dimitrov and Goffin in London
Rafael Nadal and Roger Federer were drawn in Group Pete Sampras and Group Boris Becker respectively on Wednesday.
World number one Rafael Nadal has been drawn to face Dominic Thiem, Grigor Dimitrov and David Goffin in the group stage of the ATP Finals.
Nadal's participation has been in doubt due to a knee injury which forced him to pull out of the Paris Masters, but the top seed was on Wednesday drawn in Group Pete Sampras for the tournament in London.
The Spaniard has never won the season-ending event and will be eyeing his seventh title of the year at the O2 Arena, fitness permitting.
Second seed Roger Federer leads Group Boris Becker and will face Marin Cilic in a repeat of the Wimbledon final, which the Swiss great won in straight sets back in July.
Federer has won both tournaments he has entered since losing to Juan Martin del Potro at the quarter-final stage of the US Open and will be bidding to win the ATP Finals title for a seventh time.
Third seed Alexander Zverev and Jack Sock – who came from nowhere to secure the final qualification spot by winning the Paris Masters on Sunday – will be up against Federer in the round-robin stage.
ATP Finals draw:
Group Pete Sampras
 Rafael Nadal
 Dominic Thiem
 Grigor Dimitrov
 David Goffin
Group Boris Becker
 Roger Federer
 Alexander Zverev
 Marin Cilic
 Jack Sock