Despite concerns over his elbow, Novak Djokovic is set to play at the Davis Cup Finals.
For the fifth time in his career, Spanish great Rafael Nadal will finish the year as world number one.
Novak Djokovic exited the ATP Finals after a straight-sets loss to Roger Federer, who said: "It was definitely magical."
Rafael Nadal clinched the year-end number one after Roger Federer eliminated Novak Djokovic from the ATP Finals.
Matteo Berrettini became the first Italian to win an ATP Finals match, beating Dominic Thiem in straight sets on Thursday.
Tennis' most successful doubles team of all time, brothers Mike and Bob Bryan, have announced they will retire after next year's US Open.
Alexander Zverev beat Rafael Nadal in his ATP Finals opener but was no match for world number six Stefanos Tsitsipas on Wednesday.
Daniil Medvedev would have won his ATP Finals match against Rafael Nadal 999 times out of 1000, according to the world number one.
Daniil Medvedev looked destined to leave Rafael Nadal on the brink of ATP Finals elimination, but the world number one surged back to win.
Tomas Berdych will make an announcement in London on Saturday, when it is widely expected he will confirm his retirement.