Swiss tennis legend Roger Federer has announced on Instagram that he will miss the US Open, beginning August 30, and "many months" after undergoing knee surgery.

"I just wanted to give you a bit of an update [on] what's been going on since Wimbledon. As you can imagine, it's not been simple. I've been doing a lot of checks with the doctors as well on my knee, getting all the information as I hurt myself further during the grass-court season and Wimbledon," Federer said in a video posted late on Sunday, which was also put up on atptour.com.