20-time Grand Slam single's winner Roger Federer has withdrawn from the Tokyo 2020 Olympics with a knee injury.

The 39-year-old announced through social media that he is "greatly disappointed" that he will not be able to represent Switzerland at the games that begin on July 23.

"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 wrote.

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

"I have already begun rehabilitation in the hopes of returning to the tour later this summer. I wish the entire Swiss team the best of luck and I will be rooting hard from afar," he concluded.

Federer now joins another Tennis great, Rafael Nadal in missing the Tokyo Games.

Federer won the 2008 Olympic gold medal in the men's doubles tennis tournament alongside Stanislas Wawrinka.

The 39-year-old also has won the silver medal in singles from the 2012 London Olympics.