
Roger Federer returns to action Friday at the Miami Open after missing two months due to a knee injury.

How did the Swiss get hurt? He speculated he tweaked his left knee while running a bath for his twin daughters. Federer then underwent surgery for the first time in his career.

But Federer isn't the only grand slam winner to suffer from a strange mishap. In 2011 in Cincinnati, Rafael Nadal burnt some of his right fingers while holding a hot plate at a restaurant.

Serena Williams, shortly after winning Wimbledon in 2010, stepped on broken glass at a restaurant in Germany -- she was wearing sandals at the time -- and had to have an operation on her right foot.

Kim Clijsters, meanwhile, twisted her right ankle while dancing at her nephew's wedding in 2011.

Federer's opener in Miami comes against someone who knows a lot about injuries, Juan Martin del Potro, though the Argentine's wrist woes have hardly been unconventional.

Del Potro stunned Federer to win his first -- and only -- grand slam title at the 2009 U.S. Open.