On June 20, 1973, Billie Jean King and 62 of her fellow players gathered at London's Gloucester Hotel to deliver a pre-Wimbledon bombshell -- the formation of the Women's Tennis Association (WTA).
Forty years on, their contemporaries, most of whom are already multi-millionaires, are still battling to convince the doubters that their cause was just.
"Has it really been 40 years?" asked King. "What started as a few women and a dollar has grown to thousands, living the dream -- our dream.
"We were athletes who wanted to compete and along the way we made history, determined to win, not just for ourselves but for women everywhere. Once we got started we were unstoppable."
King, who collected 39 Grand Slam titles in her career, was furious over the discrepancies in prize money offered to men and women by the tour bodies in the 1970s.
For her and other top players, it was an embarrassing relic in an era when an awareness of women's rights was becoming increasingly more volatile and militant.
For example, at Wimbledon in 1973, the men's champion Jan Kodes took home a cheque for 5,000 pounds while King had to settle for just 3,000.
However, it was not until 2007 that Wimbledon, the two-week grasscourt Grand Slam that starts in southwest London next week, finally agreed to pay their champions the same amount.
Even that was a step too far for some, with French top 20 player Gilles Simon insisting as recently as last year's Wimbledon that most of the men on the professional tour were not convinced.
"Men players? The 128 players here think like me, that's for sure. Just ask them," he said.
"Maybe they can't say it; maybe they won't; maybe they will lose $2 million on the contracts if they say that."
"We often speak of equal money but I think it's something that doesn't work in sport. Tennis is the only sport today where we have parity, even though men's tennis remains more attractive than women's."
Comments like that reminded many in the sport of King's other cause celebre of 1973 -- her famous Battle of the Sexes match against 1939 Wimbledon and US men's champion Bobby Riggs.
Riggs, who was 55 at the time, insisted that women's tennis was far inferior to the men's game.
Having already defeated Australian great Margaret Court earlier in the year, he believed he could further illustrate his point by beating King, 26 years his junior.
But at a packed Houston Astrodome on September 20, 1973, King won, 6-4, 6-3, 6-3, running the old man ragged.
The Sunday Times in London described the victory as "the drop shot and volley heard around the world".
King insisted the occasion, which had seen her enter the arena on a gold litter carried by four muscle-bound hunks dressed as slaves and Riggs wheeled on in a rickshaw by scantily-clad models, was a serious exercise.
"I had to beat him for a lot of reasons. But it wasn't about a tennis match -- it was about social change," she said.
Prior to the formation of the WTA in 1973, the annual prize money available to professional female tennis players was close to $2 million.
In 2013, it is $118 million (88 million euros, £75 million) across 54 tournaments in 33 countries and the four Grand Slams.
Winners of this year's Wimbledon men's and women's events will each receive £1.6 million -- up £450,000, or 39 percent, from last year, the All England Club that runs the tournament announced in March.
The massive increase in prize money across the board is King's legacy, according to WTA chief executive Stacey Allaster.
"One of the most powerful things about the WTA is how much our current generation of players is inspired by Billie Jean King and the rest of the game's pioneers, who have paved the way for the success that the WTA is enjoying today," she said.