They called it the Association of Tennis Professionals (ATP) and it has been spearheaded by some of the biggest names ever since.

Roger Federer, who retires this week, won 20 Grand Slam singles titles including a record eight at Wimbledon and is one of its most distinguished members.

He enjoyed epic rivalries with Rafael Nadal and later Novak Djokovic and Sir Andy Murray, but it is perhaps appropriate that his farewell should come in the Laver Cup, an event named in honour of a legendary tennis figure from an earlier era - Rod Laver.

Laver won 11 major singles titles including two calendar Grand Slams, but there are many who believe he would have been even more successful had he not been barred for five seasons after turning professional.

In 1962, Laver was only 24, but he won in his native Australia, France, at Wimbledon and completed the calendar Grand Slam in the United States where he defeated his compatriot Roy Emerson, another revered champion, over four sets. 

In those days, the tournament was called the US National Championships and played at Forest Hills.

At the end of the season, Laver turned professional, though the sums on offer were hardly eye-watering by today’s standards.

In 1962, it was reported that the winner of one professional singles tournament in the South of France was to receive approximately $800 (£707/ €809) for his trouble.

There had been professional tennis since the 1920s when the legendary French player Suzanne Lenglen was an early attraction. In the 1930s, Americans Bill Tilden and Donald Budge both turned professional after successful amateur careers as did Britain's Fred Perry.

All were banned thereafter from taking part in the Grand Slams.

American player Jack Kramer had been Wimbledon men's singles champion in 1947 and also won the US Championships twice in the same era, but as his playing career came to an end, he began promoting professional tennis.

The post-war circuit Kramer organised included star players such as the flamboyant Pancho Gonzales, US champion in 1948 and 1949, Tony Trabert, who had won Wimbledon, the US and French Championships in the mid 1950s, and Australian Lew Hoad, twice a winner at Wimbledon who had also won Australian and French titles.

"Without any second thoughts, I would say that Jack Kramer was the single most significant figure in the history of his game," Frank Deford wrote in Sports Illustrated many years later.

By the mid 1960s, an increasing number of amateur players decided to turn professional and in 1967, the National Tennis League and World Championship Tennis (WCT) both came into being.

There had been an increasing wish on both sides to bring the sport back together.

"The amateurs have got the tournaments and we have the players," Kramer complained.

In 1967, the Lawn Tennis Association in Britain proposed a limited number of Open tournaments.

Though this was originally resisted by some, the first Open tournaments were held in 1968. For the first time, Wimbledon and the other Grand Slams were open to entries by professionals.

Laver meanwhile astounded the tennis world by completing another calendar grand slam in 1969.

His earnings from a career which spanned 23 years were reported as $1.5 million (£1.3 million/€1.5 million).

In 2022, the US Open singles champions received $2.6 million (£2.3 million /€2.6 million).

In the early 1970s, the players felt they still lacked a voice in the sport. 

There had been a dispute which saw some players affiliated to the WCT excluded. They included Laver, his Australian compatriots John Newcombe and Ken Rosewall, and the American Arthur Ashe who had won the 1968 US Open, the first to be open to professionals.

In August there were discussions about forming a players' representative body.

"We are tired of being stepped on by two elephants," Ashe said, a reference to both the International Lawn Tennis Federation (ILTF) and the WCT.

"They are good organisations but sometimes don’t consider the players," Ashe complained.

Eventually some 70 players convened under the centre court stands of West Side Tennis Club at Forest Hills, in September 1972 at the US Open to discuss the future.

Kramer and agent Donald Dell lobbied support for the new venture.

Sixty players signed up for the new ATP which undertook to "unite, promote and protect," the interests of its members. Its foundation was welcomed by many.

"At last a players’ organisation seems to have a real chance of turning into a force in the game," predicted the respected tennis writer David Gray. 

South African player Cliff Drysdale was named as the first President.

Other Board members included Laver, Ashe, Gonzales and Ion Tiriac, later to manage Boris Becker.

Kramer was made executive director, an appointment widely praised by those in the sport.

"We now have a powerful organisation," Ashe insisted.

The following year, the ATP had its first major occasion to flex the muscles. Croatian Niki Pilic had refused to play a Davis Cup match for Yugoslavia against New Zealand in May, preferring to play in a match on the tour in Las Vegas.

He was banned by his National Federation and then by the ILTF - now known as the International Tennis Federation.

"He let them down very badly," ILTF secretary Basil Reay insisted as he enforced the ban.

"We have the fullest confidence in our cause," Drysdale countered on behalf of the ATP. "We deeply regret that this confrontation came in Wimbledon fortnight, but we had little choice."

Both sides refused to back down.

There was a legal challenge but this failed.

Eighty-one players boycotted the 1973 Wimbledon men's tournament in protest.

In the men's final, Czech player Jan Kodeš defeated Alex Metreveli of the Soviet Union.

The episode demonstrated that the players now had a powerful voice.

It was said to have inspired the women, led by Billie Jean King, to do something similar.

A group of players, among them King's American compatriot Rosie Casals, Australia's Margaret Court and Francoise Durr of France, had already signed up for a women's tour.

King convened a meeting which established what would eventually became known as the Women's Tennis Association (WTA).

The balance of power in international tennis had changed forever.