Novak Djokovic paid a warm tribute to his rival Roger Federer on Friday, saying they had enjoyed "a decade of incredible moments and battles" after the Swiss great's announcement that he will retire after the Laver Cup this month.
Djokovic, reacting 24 hours after Federer said he was quitting, said on social media: "Your career has set the tone for what it means to achieve excellence and lead with integrity and poise.
"It's an honour to know you on and off court, and for many more years to come."
Rafael Nadal also congratulated Federer on his extraordinary career while Serena Williams welcomed the 41-year-old Swiss to the "retirement club" after the American herself quit the game this month.
On Thursday, Federer admitted his battles with a knee problem had forced him to call time on a historic career that has yielded 20 Grand Slam titles and earned him a reputation as one of the most elegant players the game has ever seen.
It was not a total surprise as he has been out of action since a quarter-final loss at Wimbledon in 2021. After that match he underwent his third knee surgery in 18 months as time caught up with him.
Federer said in a social media statement that his 24 years on the tour had been "an incredible adventure".
"While it sometimes feels like it went by in 24 hours, it has also been so deep and magical that it seems as if I have already lived a lifetime," the Swiss said.
Knee problems restricted him to only three of the 11 Grand Slams played since the start of 2020 and he said his body had sent him "a message".
"Tennis has treated me more generously than I ever would have dreamt, and now I must recognise when it is time to end my competitive career."
Djokovic, who is six years younger than Federer and has collected Grand Slam titles as the Swiss player's powers have dimmed, had been conspicuous by his absence among the tributes on Thursday.
But a day later he said: "Roger, it's hard to see this day and put into words all that we've shared in this sport together."
The duo played 17 matches at Grand Slam tournaments, including five finals, with Djokovic leading that head-to-head 11-6.
Tennis has now lost two of its greatest names in quick succession, after the 40-year-old Williams bowed out following a third-round defeat at the US Open this month.
"I wanted to find the perfect way to say this, as you so eloquently put this game to rest – perfectly done, just like your career," Williams, who won 23 major titles, said on Instagram.
"I have always looked up to you and admired you. Our paths were always so similar, so much the same. You inspired countless millions and millions of people – including me – and we will never forget."
Nadal, arguably Federer's greatest on-court rival, said it had been "an honour" to face him.
The pair played 40 times, including nine Grand Slam finals, with Nadal holding a 24-16 winning record.
"It's a sad day for me personally and for sports around the world," Nadal tweeted.
Federer will finish his career behind only Nadal, with 22, and Djokovic, with 21, on the all-time list for most men's Grand Slam titles.
Djokovic held a 27-23 winning record over Federer from 50 meetings.
Wimbledon, where Federer won a record eight titles, also paid Federer a handsome tribute.
"It's been a privilege to witness your journey and see you become a champion in every sense of the word," the organisers tweeted.
Teenager Carlos Alcaraz, the up-and-coming man in tennis having won the US Open last Sunday to become the youngest-ever world number one, tweeted a broken heart emoji.
The Laver Cup promises to be an emotional final meeting of the "Big Four" who have dominated men's tennis over the past two decades.
Nadal, Djokovic and two-time Wimbledon champion Andy Murray will all play for Team Europe.
"I was lucky enough to play so many epic matches that I will never forget," Federer said, giving his own nod to his rivals.
"We pushed each other, and together we took tennis to new levels."
Federer, who won 103 ATP titles, had said in July he hoped to play one more Wimbledon. He departs with regrets but added he had lived a life that many would envy.
"I consider myself one of the most fortunate people on Earth," he said.
Federer won the last of his Slam titles at the 2018 Australian Open and last played in a major final at Wimbledon three years ago, losing to Djokovic despite holding two championship points.