With the advent of the tennis' Open era, the founding of an global professional tennis tour, and incomes from the sales of television rights, the game of tennis has expanded throughout the world and has got rid its English-speaking upper-class representation. Since the 1970s big men's singles and women's singles champions have come out from the former Czechoslovakia (Martina Navratilova, Ivan Lendl and Hana Mandlikova), Germany (Steffi Graf, Boris Becker), Sweden (Stefan Edberg, Björn Borg), Russia (Marat Safin and Yevgeny Kafelnikov), Brazil (Gustavo Kuerten), Belgium (Justine Henin-Hardenne and Kim Clijsters), Switzerland (Roger Federer and Martina Hingis), Spain (Rafael Nadal and Sergi Bruguera), and from other countries.
Among the other most prominent men's singles players of the Open era of tennis following may be highlighted: Jimmy Connors, Rod Laver, John Newcombe, Arthur Ashe, Stan Smith, Björn Borg, Ivan Lendl, Mats Wilander, John McEnroe, Stefan Edberg, Thomas Muster, Greg Rusedski, Jim Courier, Goran Ivanieviæ, Pete Sampras, Michael Chang, Andre Agassi, Lleyton Hewitt, and Andy Roddick. Among the women's singles are Billie Jean King, Margaret Smith Court, Evonne Goolagong, Chris Evert, Monica Seles, Arantxa Sánchez Vicario, Lindsay Davenport, Serena Williams, Venus Williams, Maria Sharapova, and Justine Henin-Hardenne.
Until the early 1950s, Bill Tilden was in general considered the greatest tennis player ever, his only challengers being Budge, Vines, and Kramer. In later 1950s though many believed Pancho Gonzales had taken over that title. Since then on, champions of the tennis's Open era, first Laver, then McEnroe and Borg, followed by Pete Sampras and currently Roger Federer, have been thought the best ever. However, even in the circle of tennis experts, no consent exists.
ATP men's rankings, at first only singles, were first issued 1973 and were then extended to embrace men's doubles in1976. Aside from determining the best players in the world men's rankings were devised to be used by the majority of main tennis tournaments as a starting point of deciding the entries' acceptance.
ATP men's rankings were not on the weekly basis as they are now until 1979. Here is the list containing the number of ATP men's rankings issues from 1973 and until men's doubles inclusion in 1979:
1973 -- 7 issues
1974 -- 11 issues
1975 -- 13 issues
1976 -- 23 issues
1977 -- 34 issues
1978 -- 40 issues
1979 -- 43 issues
Year-end men's rankings in the beginning were the last rankings issue of a year, or the first issue of the following year. This tradition was abolished in 1991 when ATP decided it to follow their Singles & Doubles Championships in late November.
In 2000 an additional men's single and men's doubles ranking was set up by the ATP. This was given the name of ATP Champions Race. According to it, all players begin the year having zero points and start a calendar year race. The player who accumulates maximum number of points becomes the world #1. This additional men's ranking was brought in to make things more logical and understandable for the public and to make sure that the best players took par in the most prestigious tennis tournaments.