Twelve countries will battle for the prestigious team trophy, with 2020 finalists Serbia and Spain leading the way.
Nadal defeated Djokovic 6-0, 6-2, 7-5 in straight sets in the final to win his 13th title at the Roland Garros on October 11 last year.
Federer, who did not compete after reaching this year's Australian Open semi-finals due to injury, will end the year at the number five spot.
Daniil Medvedev sent Rafael Nadal packing after a gruelling slugfest at the ATP Finals in London on Saturday to set up a title match against Novak Djokovic's conqueror Dominic Thiem.
Dominic Thiem mastered the tiebreakers again to get the better of Rafael Nadal on Day 3 of the ATP Finals.
Nadal achieved the milestone after securing a 4-6, 7-6(5), 6-4 win over Feliciano Lopez in the ongoing Paris Masters.
PV Sindhu reminisced a moment from the initial days of the Federer-Nadal rivalry that inspired her in her career.
One of the great unanswered sporting questions was answered in an emphatic manner on Sunday.
One 'GOAT' to another: Roger Federer's warm message to Rafael Nadal after latter's record-equalling French Open win
Nadal demolished Novak Djokovic 6-0, 6-2, 7-5 to add a 13th Roland Garros to his four US Opens, two Wimbledons and one Australian Open crown.
Rafael Nadal destroys Novak Djokovic to win 13th French Open, equals Roger Federer's Grand Slam record
For world number one Djokovic, the defeat ended his hopes of an 18th Slam and of becoming the first man since Rod Laver in 1969 to win all four majors twice.
This match carries significant weight in the Grand Slam standings that so many fans, and the players themselves, keep tabs on.
Djokovic is chasing an 18th Grand Slam title while Nadal is chasing his 20th.
For 34-year-old Nadal, it was a 99th win at Roland Garros since his 2005 debut and put him just one victory away from equalling Roger Federer's all-time record of 20 Grand Slam titles.
Nadal, the 12-time champion, defeated 19-year-old Sinner 7-6 (7/4), 6-4, 6-1 to clinch a 98th victory in his 100th match at the French Open.
Twelve-time French Open champ Rafael Nadal has dropped just 19 games through his opening three matches at this year's tournament.