Tennis pro tours and tournament ranking series

For many years before the Open Era of tennis in 1968, the usual format for the handful of touring tennis professionals was a series of two-man one-night stands across the United States and often in other countries as well. The most notable of these tours were the "World Series"^[1][2] or "World Professional Championships",^[3][4][5][6] in which the reigning world champion went head-to-head against a challenger, most often the leading amateur of the previous year who had just turned pro. Promoters would attempt to sign the leading amateur to a contract with a minimum guarantee against a percentage of gate receipts, making a similar type of deal with the reigning professional champion and sometimes giving smaller percentages to undercard players. The winners of the tours were described as being the "world champion".^[7]

After World War II, with an increasing number of prominent professional players, there were occasionally tournament series with point systems which created official rankings for the complete field of pros. The tournament ranking series were held in 1946, 1959 and 1960 and there were also World Championship tours in these same three years involving only a few pros. The last World Championship two-man tour was held in 1963, featuring a final set of matches of Ken Rosewall against Rod Laver. From 1964 until 1967, a tournament series with a point system determined the pro No. 1 player. Some shorter two-man or four-man tours continued to be held from 1964 onward, as there had been since the late 1920s, but without a world title at stake.^[8]