Bangkok, Thailand (Sports Network) - Serena Williams was forced to withdraw from an exhibition match in Thailand later this month after undergoing surgery on her big toes.

The 15-time Grand Slam singles titlist and former top-ranked star was scheduled to meet current No. 1 Victoria Azarenka in Hua Hin on December 29, but China's Li Na will now fill in for the American great.

Williams "was treated for a chronic foot disorder which involved minor procedures on both of her great toes," according to Florida podiatrist Jeffrey Rockefeller. "She needs to minimize activity to fully recover."

The 31-year-old Williams is expected to play at the Australian Open next month.

Williams was named the WTA Player of the Year after winning Wimbledon, the U.S. Open, London Olympics, and season-ending Championships.

The Sports Network