Serena Williams has won her second career WTA Championship title with a commanding 6-2, 7-6, 7-4 victory over her sister Venus Williams at Doha. It was Serena's second season-ending trophy to add to her 2001 success and made her just the second player after Justine Henin in 2007 to win two Grand Slam titles as well as the WTA Championship in the same year. The 85 minute win was Serena's 13th Victory in 23 meetings with her sister, a family rivalry stretching back to 1998.