Swiss tennis star Roger Federer has withdrawn from the Tokyo Olympics after suffering a “setback” with his knee during the grass-court season. He said Tuesday “I unfortunately experienced a setback with my knee, and have accepted that I must withdraw from the Tokyo Olympic Games,” Federer said in a Twitter post Tuesday. “I am greatly disappointed, as it has been an honor and highlight of my career each time I have represented Switzerland. “I have already begun rehabilitation in the hopes of returning to the tour later this summer.” Federer, who has 20 Grand Slam titles, was beaten at Wimbledon in the quarterfinals by Hubert Hurkacz 6-3, 7-6 (4), 6-0. Federer, who turns 40 on Aug. 8, had said before Wimbledon that he would make a decision about going to the Summer Games after the Grand Slam tournament ended. Federer won a gold medal alongside Stan Wawrinka in doubles at the 2008 Beijing Olympics and a silver in singles at the 2012 London Olympics, losing to Britain’s Andy Murray in the final at the All England Club. Federer sat out the 2016 Rio de Janeiro Games because of problems with his left knee.