Clijsters has been ranked as the 14th-greatest women's tennis player in the Open Era by "Tennis.com". Her 41 singles titles are the 14th-most in the Open Era. Since 2000, only the Williams sisters, Justine Henin, and Maria Sharapova have won more than her four Grand Slam singles titles. The three titles she won at the WTA Tour Championships are tied for the fifth-most in history behind only Martina Navratilova, Steffi Graf, Serena Williams, and Chris Evert. Clijsters was a champion at all four Grand Slam tournaments, winning the French Open and Wimbledon in doubles and the US Open and Australian Open in singles. Her prowess at singles and doubles is also highlighted by her becoming one of six players in WTA history to be No. 1 in the world in both rankings at the same time.