Serena Williams sealed her fifth WTA Finals title. In the title clash in Singapore today, the 18-time Grand Slam-winner hammered Simona Halep of Romania in straight sets 6-3, 6-0.Proving she remains on top of women's tennis at the age of 33, Williams also became the first player to win the season finale three times in a row since Monica Seles in 1992. Williams picked up the $2,047,000 winner's cheque along with the Billie Jean King trophy, which she also lifted in 2001, 2009, 2012 and 2013.