20-time Grand Slam champion Federer announced on Thursday that he would retire after next week Cup of the tank.
“Roger, it’s hard to see this day and put into words everything we’ve shared together in this sport,” Djokovic wrote on Instagram, saying they had “over a decade of amazing moments and battles to reflect on.”
Djokovic and Federer have faced each other 50 times, with the Serb holding a winning record of 27-23.
The duo have played 17 matches at Grand Slam tournaments, including five finals, with Djokovic leading that head-to-head 11-6.
“Your career has set the tone for what it means to achieve excellence and lead with integrity and confidence,” added the 35-year-old.
“It is an honor to know you on and off the pitch, and for many years to come.”
Federer’s last grand final was the epic showpiece of Wimbledon in 2019, won by Djokovic in a final-set tie-break after the Swiss had already missed two championship points.
Federer, 41, trails only ‘Big Three’ rivals Djokovic (21) and Rafael Nadal (22) on the all-time list of most men’s Slam titles.
The trio will play together in London next week at the Laver Cup as part of Team Europe in the final event of Federer’s career.
“Looking forward to celebrating your achievements and seeing you in London,” Djokovic said.