Sania Mirza and her Zimbabwean teammate Cara Black have lifted the Doubles trophy of the WTA Finals Singapore. In the finals today, the third seeded Indo-Zimbabwean pair needed just 59 minutes to beat second seeds, China's Shuai Peng and her Taiwanese partner Su-Wei Hsieh, in straight sets, 6-1, 6-0.This was Saina's maiden WTA Finals doubles title, while Cara Black won the title for the third time. The victory was the duo's fifth title in their 13-month spell together.In the Singles, world number one Serena Williams will clash with Simona Halep of Romania in the final today. Simona had stunned 18-time Grand Slam-winner and two-time defending champion Serena in the group stage of this tournament, beating the American in straight sets, 6-0, 6-2.