List of Grand Slam men's singles champions
Updated: Wikipedia source
Many changes in the Grand Slam tennis tournaments have affected the number of titles won by various players during its history. These changes have included the opening of the French national championships to international players in 1925, the elimination of the challenge round in 1922, and the admission of professional players in 1968 (the start of the Open Era). All of these tournaments have been listed based on the modern definition of a tennis major, rather than when they were officially recognized by the ILTF. The Grand Slam tournaments are the annual four major tennis events played in the Open Era, which began in 1968, superseding the Amateur Era. The Australian and U . tournaments were officially recognized by the ILTF in 1924, and the French Championships followed a year later in 1925 when it became open to all international players. The United States Lawn Tennis Association (USLTA) had several grievances with the ILTF and refused to join when it was formed in 1913. From 1913 to 1923, there were three official championships recognized by the ILTF:
World Grass Court Championships – Wimbledon. World Hard Court Championships, held in Paris on clay courts. World Covered Court Championships, held in Europe on an indoor wood surface. During that same time period the USLTA recognized the U . National Championships
U . National Championships, held in New York on grass.