Serena Williams has withdrawn from her scheduled exhibition match against world No.1 Victoria Azarenka in Thailand later this month due to toe surgery.
The American world No.3, who ended the 2012 season in style by winning the US Open and WTA Championships in Istanbul, recently underwent surgery on her big toes but needs time to recover from the operation.
A medical certificate from Florida podiatrist Jeffrey Rockefeller revealed the 31-year-old "was treated for a chronic foot disorder which involved minor procedures on both of her great toes."
Williams, who will be replaced by Li Na for the exhibition match on December 29 in Hua Hin, added: "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."
Williams is still expected to return to action in the Brisbane International, which starts on 30 December, with tournament director Cameron Pearson saying he had been assued by her agent she would be 'fit and ready'.
She has been troubled by chronic foot problems since treading on glass and badly cutting both feet back in 2010.