Roger, over and out, signs off on season

Roger Federer is sitting out the rest of this season, including the Rio de Janeiro Olympics and the US Open, in order to protect his surgically repaired left knee.

Federer wrote on his Facebook page on Tuesday that he needs "more extensive rehabilitation following my knee surgery earlier this year."

"The doctors advised that if I want to play on the ATP World Tour injury-free for another few years, as I intend to do, I must give both my knee and body the proper time to fully recover," said the Swiss superstar.