Grand Slam (tennis) tennis ball, Martina Navratilova finally did it." Although the ITF recognizes what is now unofficially known as the "non-calendar year Grand Slam" on its Roll of Honour, no subsequent player to win four or more majors in a row—Steffi Graf, Serena Williams, or Novak Djokovic—has received bonus prize money. Combining "the" Grand Slam and non-calendar year Grand Slam, the total number of times that players achieved the feat (of being the reigning champion in all four majors) expands to 18. Three women have won four or more consecutive major titles since 1970, with Navratilova taking six in a row in
Grand Slam (tennis) clay, and Wimbledon on grass. Wimbledon is the oldest, founded in 1877, followed by the US in 1881, the French in 1891, and the Australian in 1905. However, of these four, only Wimbledon was a major before 1924–25, when all four became designated Grand Slam tournaments. Skipping majors—especially the Australian Open because of the remoteness, the inconvenient dates (around Christmas and New Year's Day) and the low prize money—was not unusual before 1982. Grand Slam tournaments are not operated by the Association of Tennis Professionals (ATP) or the Women's Tennis Association (WTA), but by the International Tennis Federation (ITF). However,