Roger Federer reveals his knee injury was caused by running a bath for his twin daughters

Federer was forced to undergo surgery on a torn meniscus last month

Roger Federer has revealed the reasoning behind his knee injury last month (Getty Images)

Roger Federer has revealed the cause behind the knee injury that forced him to undergo the first surgical operation of his career earlier this year, after hurting it while running a bath for his twin daughters.

The 17-time Grand Slam champion was knocked out of the Australian Open in January in the semi-finals by eventual winner Novak Djokovic, and was forced to undergo surgery a few days later when he revealed that he had suffered a torn meniscus.

Ahead of his planned return at the Miami Open this week, Federer explained the cause of the injury, which occurred in rather bizarre circumstances.

"I think I was going to run a bath for the girls," he said.

"I made a very simple movement, turned back, heard a click in my knee. I went to the zoo. My leg was swollen."

Roger Federer will return to action at the Miami Open this week (Getty Images)

While the 34-year-old Swiss has not missed any Grand Slam tournaments, he did express a sadness at needing surgery for the first time in his career, having hoped to retire from the game without having to go under the knife.

"I thought I was going to get through my career without any," Federer added. "It was a big shock and, yeah, disappointing."

Roger Federer's last outing came in the Australian Open loss to Novak Djokovic (Getty Images)

Federer is in the United States this week to make his return in the Miami Open, where he takes on Argentina’s Juan Martin del Potro in the second round after receiving a first round bye.

The revelation sees Federer join a select group of professional sportsmen who have suffered injury away from competition in the weirdest way possible.

Click on the gallery below to see sports weirdest injuries.

Federer was forced to miss seven weeks after recovering from arthroscopic surgery.