Federer out for a month after knee surgery

World No.3 tennis star Roger Federer has undergone a knee surgery and is expected to be out of action for a month.

The 34-year-old had the surgery in his native Switzerland to repair a torn meniscus muscle. He was injured last week during his Australian Open semi-final defeat by eventual champion Novak Djokovic.

The 17-time Grand Slam champion has withdrawn from the World Tennis Tournament in Rotterdam and the Dubai Championships later this month.

"I want to inform you that yesterday I underwent arthroscopic surgery on my knee," he wrote on Facebook on Wednesday.

"I injured my knee the day after the semi-finals in Australia. After getting tests done when I returned home, it was determined that I had torn my meniscus. I apologise to my friends in Rotterdam and Dubai (the tournaments he will miss), as I was very much looking forward to playing those events."

"While this is an unfortunate setback, I am encouraged and grateful that my doctor said the procedure was a success. I am looking forward to attacking the rehabilitation process this afternoon with my team and working hard to get back out on tour as soon as possible."

"Thanks for all your incredible support. I will check in with all of you soon."