Roger Federer has to undergo a third operation on his right knee and will again not be able to play for months. The 40-year-old Swiss announced this on Instagram on Sunday. This means that the winner of 20 Grand Slam tournaments for the US Open, which starts in two weeks, will be canceled and probably also for the rest of the season. Federer had to undergo two knee operations last year and, according to his own statements, injured himself again during the lawn season. After his quarter-final at Wimbledon, he was absent from the Olympic Games in Tokyo and also from the preparatory tournaments for the US Open that are now taking place in North America. Federer did not speak of an end to his career in the message. He wants to give himself the chance to return to the tennis tour again.