Jack Sock is having quite a finish to 2017. He won his first Masters Series tournament, broke into the top 10 in the tennis rankings for the first time and earned his first berth in the ATP Finals.
Sock is the first American man to reach the season-ending event since 2011.
He will face 19-time Grand Slam champion Roger Federer when play begins Sunday in London.
In Wednesday's draw for the round-robin format, Sock was put in a group with Federer, 2014 U.S. Open champion Marin Cilic and Alexander Zverev.
The other group has 15-time Grand Slam title winner Rafael Nadal, Dominic Thiem, Grigor Dimitrov and David Goffin.