Serena Williams wins WTA Tour Player of the Year award

Serena Williams has been named WTA Tour Player of the Year for the fourth time after winning Wimbledon, the US Open and Olympic gold in 2012.

The American struggled at the start of the year and went out of the Australian Open in the fourth round.

Why is Serena not ranked No 1?

The WTA rankings are based on a 52-week cumulative system. They must include points from the Grand Slams, Premier Mandatory tournaments and the WTA Championships. Serena did not compete in Beijing and Indian Wells, two of the four Premier Mandatory tournaments. She only received five points from a possible 2000 after going out in the first round of the French Open, and 280 points from a possible 2000 for her fourth round Australian Open defeat.

However, tournament victories in Charleston and Madrid in April and May set up the world number three for a run of 48 wins in 50 matches.

Williams previously won the WTA award in 2002, 2008 and 2009.

William, 31, ended her year by winning the WTA Tour Championships in Istanbul, beating Maria Sharapova 6-4 6-3 in the final.

She finished the season third in the world rankings behind Victoria Azarenka and Sharapova, but could regain the world number one ranking for the first time since October 2010 if she wins the Australian Open in January.

Williams is one of only three players to win the award more than twice in its 36-year history, alongside eight-time winner Steffi Graf and seven-time winner Martina Navratilova.