Serena Williams recovers from surgery on her toes
Serena Williams had to undergo surgery on both her big toes as a treatment for "a chronic foot disorder which involved minor procedures on both of her great toes". So as not to hamper the recovery process, Serena will not play the Thailand exhibition against Victoria Azarenka, scheduled for December 29th in Hua Hin. Li Na will be her replacement.
Last year Azarenka also played the Hua Hin exhibition when she defeated Caroline Wozniacki. Serena is expected to open her 2013 season at the Brisbane International. (source: ESPN, photo courtesy of Fiji Water)
to serena's fans : the surgery can cause temporary pain but serena will be ready in time to compete at Brisbane… (confirmation from her agent).. The surgery was at 13 december and serena need 2 weeks to be 100% fit, so she has enough time
best of luck serenaaaaaaa 
Fifi, thanks for the update and additional info.