American tennis player Serena Williams will finish the 2014 season on top of the rankings, the fourth time in her career that she will be the year-end No. 1 after topping the pile previously in 2013, 2009 and 2002.

The 33-year-old leads the Women's Tennis Association (WTA) tour with six titles this campaign, including the US Open. She entered the BNP Paribas WTA Finals Singapore as the top seed, and is also slated to play Simona Halep for the championship on Sunday night.

Said Stacey Allaster, chairman and CEO of the WTA: "Serena continues to prove that she is one of the greatest athletes of all time and ending the year No.1 once again further solidifies her legacy. The year-end No.1 ranking is earned through consistent excellence throughout the year - especially great results at major events.

"Serena's US Open win and five WTA Premier titles has allowed her to stay at the top as the world's greatest, an extremely deserving honor."

In the doubles, meanwhile, Italians Sara Errani and Roberta Vinci will be the top year-end doubles team for the third year running. They captured five titles in 2014, including the Australian Open and Wimbledon. The duo were forced to retire in their quarter-final in Singapore after Errani was injured.