In 1968, the commercial demands and rumours of some amateurs taking money under the table led to the abolition of this distinction, inaugurating the now established Open Era, in which all players were able to participate in all the competitions, and the best players were able to make a living off tennis.

Since the beginning of the Open Era, the creation of an international professional tennis circuit and royalties from the selling of TV rights, the popularity of tennis has expanded throughout the world, and the sport has lost its upper-and middle-class English-speaking profile, although it is acknowledged that this stereotype still exists. Before the introduction of the Open Age of tennis competitions in April 1968, only amateurs were permitted to play in existing tournaments, including the four Majors.

There was no prize money, and players were only paid for travel costs. However, many of the top tennis players turned professional to lawfully play prize money in the years before the open era. These players played in separate professional events, often on tours containing head-to-head matches, but also in professional tournaments as the biggest events on the pro tour. Professional tournaments, particularly professional Majors, generally had just a men's draw. In addition to head-to-head tours, there have also been major pro competitions, mostly contested by the world's best elite male players.

Brian Baker serves to Xavier Malisse of Belgium during the second round of the US Open. (Getty).jpg

Everything you need to know about the Pro Slam

The oldest was the Professional Majors, or "Pro Slams" was the U.S. Pro Tennis Tournaments, played in a number of places and on a variety of various surfaces between 1927 and 1999. It was played indoors in Cleveland between 1954 and 1962 and was dubbed the World Professional Championships.

A player who won all three in a calendar year was deemed to be a "Professional Grand Slam" or "Pro Slam" The feat was achieved twice: by Ken Rosewall in 1963, and by Rod Laver in 1967. Three other players won the three major trophies in their playing careers: Ellsworth Vines, Hans Nusslein and Don Budge.

Ken Rosewall is an Australian former world champion in tennis and professional tennis. He won 23 tennis Majors Record, including 8 Grand Slam singles and 15 Pro Slam record titles in the run up to the Open Era. In 1963 he gained the Pro Grand Slam. Rod Laver, retired tennis player from Australia. He ran No. 1 from 1964 to 1970, four years before and three years after the Open Era started in 1968. In 1967 he also won eight pro-Slam titles including a "pro Grand Slam" and at one age when the Davis Cup was considered as important as all four major titles, he led to Australia's five Davis Cup titles.

The 1930s U.S. tennis champion Henry Ellsworth had either been the No. 1 or co-No World player 1. He was able to win the Pro Slam championships on 3 separate surfaces over four years in 1932, 1935, 1936 and 1937. Hans Nusslein, on the other hand, was a German tennis player and coach, and a former tennis player number one in the World who won 4 major professional titles in his career. While, Don Budge is best known for winning the first four tennis tournaments in a single year—either male or female and now the only American male.

Budge was the second male player to win all four Grand Slam events in the wake of Fred Perry's career and is still the youngest player to make the accomplishment. He won 10 major, six of them Grand Slam events and four Pro Slams on 3 different surfaces. Slams, the last of them being Grand Slam events.