LONDON, England - Having won the Australian Open and Wimbledon as well as the season-ending Sony Ericsson Championships, Serena Williams has been named by the ITF as Women's Singles World Champion for 2009. The 28-year-old and her 29-year-old sister, Venus, were also named Doubles World Champions on the back of their three Grand Slam triumphs.

Serena has received the ITF honor once previously - in 2002, when she won at Roland Garros, Wimbledon and the US Open plus five other Sony Ericsson WTA Tour stops, and for the first time finished the year ranked No.1.

In 2009 the American's best performances were again delivered on the biggest stages. The victory Down Under was her fourth at Melbourne Park, while her Wimbledon win was her third there, and took her haul of singles majors to 11. Outside the Slams, Serena's best result during the main season was a runner-up finish to Victoria Azarenka at Miami, but she also reached five semifinals and her ultimate triumph at Doha enabled her to seal the year-end No.1 ranking for the second time.

The Williams sisters enjoyed the best season as a doubles unit, winning the Australian Open, Wimbledon and US Open to take their team tally of majors to 10. They also won their first non-Grand Slam or Olympic title in a decade at Stanford, but fell in the semis at Doha to eventual champions Nuria Llagostera Vives and María José Martínez Sánchez. Although Cara Black and Liezel Huber again finished the year as joint No.1s, they were beaten by the sisters at two of the majors.

Serena joins Lindsay Davenport and Martina Hingis as the only players to become singles and doubles world champions in the same year.

Sixteen-year-old Kristina Mladenovic, who won the junior title at Roland Garros, is the first French player to become Girls World Champion since Amélie Mauresmo in 1996. On the men's side, Roger Federer was named Singles World Champion for the fifth time, while Americans Bob and Mike Bryan are Men's Doubles World Champions for the sixth time in seven years.

The ITF World Champions will receive their awards at the annual ITF World Champions Dinner on Tuesday, June 1, in Paris, during Roland Garros.