Tennis' G.O.A.T. will not be in Tokyo for this summer's Olympics ... 'cause Roger Federer has just pulled out of the event due to a knee injury.
The 39-year-old made the announcement Tuesday ... saying he's suffered a setback on his right knee -- the same knee he had procedures on back in 2020.
"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.
"I am greatly disappointed, as it has been an honor and highlight of my career each time I have represented Switzerland.