Roger Federer has been drawn to face Alexander Zverev at the ATP Finals in London, one of only four players to have beaten the world No. 2 this year.
The Swiss is a six-time winner of the year-end showpiece and choose to rest rather than play the Paris Masters last week so that he could prepare for the event at the O2 Arena, which starts on Sunday.
The highly-rated Zverev, 20, should provide an early examination of the resurgent great's form after winning five titles and climbing to just one place behind Federer in the world rankings this year; they have shared two wins apiece in previous meetings.
Federer's other opponents in the round robin stage of the group -- which is named after Boris Becker -- are Marin Cilic and Jack Sock, against whom he holds 7-1 and 3-0 win records respectively.
It is a tough draw for American Sock, who clinched the final place by winning in Paris on Sunday, though he had already pledged to "swing big" and will need to if he is to progress in the tournament after securing a ranking in the top 10 for the first time in his career.
The draw looks a little kinder to Rafael Nadal if he can overcome the right knee injury which forced him to withdraw from the Paris Masters and caused problems earlier in the season.
The Spaniard, who is already guaranteed the year-end world No. 1 spot, will face out-of-form Austrian Dominic Thiem, Grigor Dimitrov, who has been nicknamed 'Baby Fed' but has beaten Nadal only once in 11 attempts, and Belgian David Goffin.
The draw -- made Wednesday -- was a closed affair in London but the ATP suffered more problems after the draw for it's NextGen Finals, for players aged 21 and under, was heavily criticised.
The men's tour had to apologise for the NextGen event in Milan last Sunday after its use of models was branded a "disgrace". On Wednesday, the draw for the senior tournament in London took place on BBC radio but Becker, who was making it, was an hour late after getting stuck in traffic.