Kim Antonie Lode Clijsters (Dutch pronunciation: [kɪm ˈklɛistərs] ; born 8 June 1983) is a Belgian former professional tennis player. She was ranked as the world No. 1 in women's singles by the Women's Tennis Association (WTA) for 20 weeks, and as the world No. 1 in women's doubles for 4 weeks, having held both rankings simultaneously in 2003. She won 41 singles titles and 11 doubles titles on the WTA Tour, including four singles majors and two doubles majors (both partnering Ai Sugiyama), as well as three singles titles at the Tour Finals. Clijsters competed professionally from 1997 in an era in which her primary rivals were compatriot Justine Henin and Serena Williams. Coming from a country with little historical success in tennis, she established Belgium as a leading force in women's tennis alongside Henin, as the two of them led their country to their first Fed Cup crown in 2001 and were the top two players in the world in late 2003. Following defeats in all of her first four major singles finals, Clijsters finally won her first singles major at the 2005 US Open. Plagued by injuries and having lost desire to compete, Clijsters retired from tennis in 2007 at the age of 23 to get married and have a daughter. She returned to the sport two years later and stunned the tennis world by winning the US Open as an unranked player in just her third tournament back. She defended the US Open title the following year and then won the Australian Open in 2011, becoming the first mother to be ranked world No. 1. Along with Margaret Court, she co-holds the record for most major singles titles won as a mother (with three), and was the first mother to win one since Evonne Goolagong Cawley in 1980. Clijsters retired again following the 2012 US Open. She had a second, short-lived comeback from 2020 to 2022. Clijsters was born to athletic parents with backgrounds in professional soccer and gymnastics. She was renowned for her athleticism, which was highlighted by her ability to perform splits on court in the middle of points. She built the offensive side of her game around controlled aggression while also using her exceptional movement to become an elite defensive player. Clijsters was very popular and well-liked as a player, winning the Karen Krantzcke Sportsmanship Award eight times. She was inducted into the International Tennis Hall of Fame in 2017.