Swiss tennis star Roger Federer says he is withdrawing from the Tokyo Olympics after experiencing "a setback” with his knee during the grass-court season.

The 39-year-old announced the news on social media.

"I am greatly disappointed as it has been an honor and highlight of my career each time I have represented Switzerland," Federer said on Twitter.

According to the Associated Press, Federer's right knee was operated on twice last year.

Federer said on Twitter that he's already begun rehabbing his knee in hopes of returning to the tour "later this summer."

Federer did not participate in the 2016 Rio de Janeiro Games because of issues with his left knee, the AP reported.