The 31-year-old 15-time Major winner is the favourite to win the event in Istanbul after triumphing at Wimbledon, winning Olympic gold, and securing her fourth US Open crown in recent months.
Williams triumphed courtesy of a walkover against Lindsay Davenport when she first won the season-ending tournament 11 years ago, and the American admitted a lot has changed in her life over the last decade after struggling with health issues in 2010 and 2011.
“I feel like back then I was really just cruising and on the rise,” said Williams. “Now in 2012, it’s a different scenario.
“I’ve been through so much in my life – triumphs, disasters, happy moments, sad moments – when your career comes complete circle like that, you really do appreciate every win more and more.”
Venus Williams secured her 44th WTA title at the weekend, beating Monica Niculescu in the Luxembourg Open final.
And Serena was delighted to see her older sister draw level with Justine Henin and Martina Hingis in terms of title wins, praising Venus’ desire despite her nearing the end of her career.
“I am so excited Venus was able to win last week,” she added.
“She’s been through so much, and to still be able to play top tennis and win tournaments is amazing. It also shows her desire, that she’s not done.
“Of course I knew it, but now other people can see she has no plans of stopping – only improving.”