Clijsters has competed professionally from 1997 in an era in which her primary rivals were compatriot Justine Henin and 23-time Grand Slam singles champion Serena Williams. Coming from a country with limited success in men's or women's tennis, Clijsters became the first Belgian player to attain the No. 1 ranking. Together with Henin, she established Belgium as a leading force in women's tennis 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. Individually, Clijsters has won 41 singles titles and 11 doubles titles on the Women's Tennis Association (WTA) Tour. She was a three-time winner of the WTA Tour Championships. Between singles and doubles, she has been a champion at all four Grand Slam tournaments, winning the US Open and the Australian Open in singles and Wimbledon and the French Open in doubles with Ai Sugiyama. Her success at majors has been highlighted by winning three consecutive appearances at the US Open.