Tennis - Serena Williams has operation on toes

Serena Williams has undegone surgery on her big toes, rocking the American's preparations for January's Australian Open.

The procedure has forced Williams to pull out of in an exhibition match against world number one Victoria Azarenka in Thailand later this month.

A medical certificate from Florida podiatrist Jeffrey Rockefeller said Williams “was treated for a chronic foot disorder which involved minor procedures on both of her great toes.”

The problem with her toes began when the 2012 WTA Tour player of the year stepped on broken glass on her way out of a restaurant in Munich in 2010.

"I am being advised by my doctors to take more time to heal following a minor procedure I needed to address my ongoing foot issues," said Williams, who won Wimbledon, the US Open and Olympic gold this year.

China's Li Na has replaced Williams for the match on December 29 in Hua Hin.