Novak Djokovic is going to the Tokyo Olympics, keeping alive his chance for a "Golden Slam." The 34-year-old took to Twitter to say that he had booked his flight and was proud to represent Serbia at the Olympics.

After he won the Wimbledon title for his record-tying 20th career Grand Slam title, Djokovic said he didn't know if he was going to play in Tokyo.

If the top-ranked Djokovic wins gold in men's singles and at the US Open, he would be the first male tennis player to complete a "Golden Slam" -- clinching all four Grand Slam tournaments and the Olympics in the same calendar year.

Steffi Graf is the only woman to have done it, in 1988.

While Djokovic is headed for Tokyo, Roger Federer, Rafael Nadal, Dominic Thiem and Nick Kyrgios are among the top men's players who won't be competing in the Olympics.

Earlier on Tuesday, Roger Federer announced that he is pulling out of the Games owing to a knee injury. The Olympics, in which on-site spectators will not be allowed owing to the Covid-19 pandemic, are scheduled to be held in the Japanese capital from July 23 to August 8. In a statement, he said that he had "suffered a setback" with his knee.

Federer announced the news on Twitter saying that he is "greatly disappointed" on missing out on an opportunity to represent Switzerland in the world's biggest sporting spectacle.

"During the grass court season, I unfortunately experienced a setback with my knee, and have accepted that I must withdraw from the Tokyo Olympic Games," Federer said in the statement.

"I am greatly disappointed, as it has been an honour and highlight of my career each time I have represented Switzerland," he added.

Federer won the silver medal in men's singles at the 2012 London Olympics and gold old in men's doubles at the 2008 Beijing Games.