Novak Djokovic has often been at the center of controversy for various reasons, but one of the most memorable incidents was his criticism of Roger Federer. He claimed that the Swiss wasn’t a good sport and didn’t miss a chance to "disrespect" his son during the 2006 Davis Cup.
During the team tournament, Federer-led Switzerland faced off against Djokovic-led Serbia, with the latter taking on Stan Wawrinka. Djokovic won a grueling five-setter 6-4, 3-6, 2-6, 7-6(3), 6-4 but drew criticism from Federer, who was unhappy with the then-19-year-old taking frequent medical timeouts, believing it disrupted Wawrinka’s rhythm.
The 20-time Grand Slam champion told media:
“I don’t trust his injuries. I’m serious. I think he’s a joke, you know, when it comes down to his injuries.”
Roger Federer later came under fire from Novak Djokovic’s father, Srdjan, who, in a 2016 interview with Newsweek, expressed his disapproval of the Swiss’ accusations. Srdjan believed Federer was insensitive, as Djokovic was dealing with serious health issues at the time.
“When Serbia played Switzerland in Geneva [in 2006], Novak was just 19 at the time. He had a deviation of his sinuses and couldn't breathe. He had a problem with staying in long matches and long points. And Federer tried in every possible way to disrespect him because of his breathing problem,” Srdjan said.
“He showed himself to be the best player in the world but not as a good person at that time. Nobody has ever treated Novak like this,” he added.
He also questioned Federer’s longevity in the sport, wondering why he was still competing at the age of 34:
“I don't understand why Federer is still playing tennis. Why does he still play? He's already 34.”
Federer and Srdjan had another controversial moment during the 2008 Monte-Carlo Masters while the former was up against Novak Djokovic in the semifinals. Frustrated, the Swiss turned to his opponent’s parents in the crowd and told them to "be quiet."
Roger Federer clears the air on his relationship with Novak Djokovic

Despite past differences with Novak Djokovic and his family, Roger Federer made it clear that they shared a good relationship. Speaking to the media in 2012, he admitted to being upset with Djokovic during their 2006 Davis Cup tie but said they had moved on.
"I was just upset at [Djokovic] calling the trainer out for no obvious reason against my buddy, Stan, in a five-setter," Federer said. "That was it. We had a quick chat about it in Madrid after that, and things are cool since a long time between me and him. I've always respected him."
He added:
"Have I gone out for dinner with him? No. But had many meetings with him at the [ATP Players] Council, and then now with the Grand Slams. He's been nice to work with. We've met on several occasions because of other things together. I have no issues with him, and I hope you believe me."
Federer bid farewell to tennis at 41 during the 2022 Laver Cup, representing Team Europe one last time. The 20-time Major champion's retirement ceremony saw Djokovic, Nadal, Murray, and others come together to honor him.
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