Factbox on former world number one Kim Clijsters, who has announced that she will be retiring from tennis after this year's U.S. Open:
MAKING HER NAME
* Born on June 8, 1983 in Bilzen, Belgium, Clijsters is the daughter of Belgian international footballer Leo Clijsters and national gymnastics champion Els Vandecaetsbeek.
* Made her senior tournament debut on ITF circuit in Belgium in 1997, losing in the quarter-finals.
* Quickly established her rivalry with compatriot Justine Henin in ITF circuit events in Belgium during 1998.
GRAND SLAM TITLES
* Claimed the women's doubles title at Roland Garros with Japanese partner Ai Sugiyama in 2003, and teams up with Sugiyama again to capture the women's doubles title at Wimbledon.
* Became the first Belgian to be ranked world number one in 2003 after triumphing in Los Angeles.
* Suffered for two years with injuries, but won the U.S. Open in 2005, seeing off France's Mary Pierce 6-3 6-1.
* Following a two-year break to start a family, she won the 2009 U.S. Open title to become the first mother to win a grand slam title since Evonne Goolagong triumphed at Wimbledon in 1980.
In only her third tournament back, the Belgian wildcard beat Danish ninth seed Caroline Wozniacki in the Flushing Meadows final.
* Seeded number two, she returned to New York 12 months later to be crowned 2010 U.S. Open champion, clinching the title for a third time by beating Russia's Vera Zvonareva 6-2 6-1.
* Won her fourth grand slam title with a 3-6 6-3 6-3 victory over China's Li Na in the final of the 2011 Australian Open.
PUTTING BELGIUM ON THE MAP
* Became the first Belgian to reach a grand slam final at the 2001 French Open, where she was beaten 12-10 in the deciding set by Jennifer Capriati. It remains the longest third set in a Roland Garros women's final.
* Helped Belgium to win the country's first Fed Cup title, winning all four of her singles matches throughout 2001.
* Along with Henin, she received Belgium's Trophy for National Sporting Excellence in 2002.
* In 2003 she reached her second Roland Garros final but once again left empty-handed after losing in straight sets to the newly married Henin-Hardenne.
MARRIAGE, RETIREMENT, MOTHERHOOD AND A COMEBACK
* Ended relationship with former Australian world number one Lleyton Hewitt in 2004 just weeks before their scheduled wedding date.
* Retired from professional tennis due to injuries on May 6 2007, then married American basketball player Brian Lynch in July 2007 and gave birth to a daughter, Jada Ellie, in February 2008.
* Clijsters announced in March 2009 she would also return to the WTA Tour.
* She returned to the world number one ranking in the next tournament after her Australian Open triumph by reaching the semi-finals of the Paris Indoor event in February 2011.