Djokovic (21 Grand Slam titles) and Federer (20) rank second and third on the all-time major championship list in men's tennis history behind only Rafael Nadal (22).
The superstars faced off 50 times on the ATP Tour during their decorated careers, with the final meeting coming at the 2020 Australian Open. Djokovic held a slight 27-23 advantage in those head-to-head meetings, including six wins over their last seven matchups.
Five of those clashes came in a Grand Slam final, three at Wimbledon and two in the US Open, with Djokovic winning four of those marquee matches.
"Obviously Roger is an icon of our sport and people around the world love him," Djokovic said in 2021. "They love watching him play, love seeing him around. He's very important for our sport on and off the court."
Injuries derailed the latter stages of Federer's career as he appeared in just three Grand Slam draws since the start of 2020. He still performed at a high level when healthy, reaching the 2020 Australian Open semifinals and 2021 Wimbledon quarterfinals.
His peak lasted nearly a decade, winning 17 of his 20 major titles between 2003 and 2012, and he probably would have won more during the second half of his career if not for the presence of two other dominant players in the same era, Djokovic and Nadal.
"I enjoy playing against him. I really feel like we get the best out of each other," Federer said about Djokovic in 2021. "We have different playing styles, [so] it almost depends on the day, which court we're playing on and how the matches have been leading up to that match."
The Swiss sensation's final official tournament will feature his Serbian counterpart as a teammate. Both players will represent Team Europe, alongside Nadal, Casper Ruud, Stefanos Tsitsipas and Andy Murray, against Team World in the 2022 Laver Cup next week.
Team World features Taylor Fritz, Félix Auger-Aliassime, Diego Schwartzman, Frances Tiafoe, Alex de Minaur and Jack Sock.
It makes Team Europe a heavy favorite on paper and gives Federer a golden opportunity to end his Hall of Fame career with one more tournament title.