Rafael Nadal has made a painful admission about Roger Federer after the Swiss star confirmed that he was retiring from professional tennis.
News of the 41-year-old's retirement has sparked an outpouring of tributes from right around the world, in a fitting salute to a man who has brought so much joy to millions.
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More than 19 years after winning his first grand slam title at Wimbledon in 2003, which set him on the road to be being one of the greatest players of all time, Federer took to social media to announce that his career had come to an end.
"As many of you know, the past three years have presented me with challenges in the form of injuries and surgeries. I've worked hard to return to full competitive form," Federer said.
"But I also know my body's capacities and limits, and its message to me lately has been clear.
"I am 41 years old. I have played more than 1500 matches over 24 years. 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.”
Like fans all around the world, the Swiss maestro's great rival Nadal admitted that he hoped this inevitable day would never come.
The Spaniard described news of Federer's retirement as a "sad day" for himself and sporting fans around the world.
Nadal's beautiful tribute to Federer on social media also included a series of incredible flashback photos of their time together - both on and off the court.
“I wish this day would have never come,” Nadal said in his social media post.
“It’s a sad day for me personally and for sports around the world. It’s been a pleasure but also an honour and privilege to share all these years with you, living so many amazing moments on and off the court.
"For now, I truly wish you all the happiness with your wife, Mirka, your kids, your family and enjoy what’s ahead of you. I’ll see you in London at the @lavercup."
Lleyton Hewitt among those to pay tribute to Roger Federer
Australia's Davis Cup captain Lleyton Hewitt - whose enjoyed some legendary battles against Federer over the course of his career - also congratulated the 41-year-old on a phenomenal career.
Reflecting on their time on tour together, Hewitt described the Swiss as "nearly unbeatable" and marvelled at the legacy he will leave behind for tennis.
"He was from my kind of era, I guess. We were the same age, we grew up together in juniors," Hewitt said.
"I knew Roger extremely well and probably saw him slightly different to everyone else as well, because we grew up together. But he was the greatest of that time.
"You know, obviously there are a couple of other guys now that are really putting their hand up, but he went clear easily from a grand slam perspective and really just his win-loss ratio [in the] mid-2000s era, he was nearly unbeatable.
"It was pretty much only Rafa [Nadal] that could get him, especially on the clay. But most of all he's been a great ambassador for our sport.
"I've always said that you don't want to push those guys out of the game too early.
"Everyone wants to talk about retirement. When are they going to retire? You want to hold on to those greats. They've done so many special things for our sport.
"But yeah, obviously, the body – you get to my age and his age now, and it's not easy. He's done everything in the sport that you could ever dream of."
Roger Federer's retirement a 'tough loss for tennis'
France's Richard Gasquet was another player to pay tribute to the one-of-a-kind talent that was Roger Federer.
"It is a big shock – he is a legend of the game," Gasquet said.
"It's not easy for anybody, I know it will be a big thing at the Laver Cup. I'm sure it will be wonderful there.
"It's a tough loss for tennis. It will be different after that. It's still tennis, but it won't be the same without Federer.
"I was leading 1-0 against him [head-to-head], I won in Monte Carlo – but after that I lost maybe 20 times. I'm not the only one of course, it was incredible when I got to face him.
"He is a legend of the game, everybody knows it. The technique, the charisma – everything was crazy. There is only one Roger Federer."
Federer finishes his astonishing career third on the all-time list of men's grand slam titles behind Nadal (22) and Novak Djokovic (21).
The Swiss maestro finished five seasons ranked No.1 and helped create a golden era of men's tennis as part of the 'Big Four' alongside Nadal, Djokovic and Andy Murray.
He leaves with a total of 103 tour-level titles and 1251 wins in singles matches, both second only to Jimmy Connors in the Open era, which began in 1968.
Federer's extraordinary career includes 20 grand slam titles, including a record eight Wimbledons and more than US$130 million ($A194m) in prizemoney alone - all driven by a rare grace, laser precision and a signature one-handed backhand.
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