ST. PETERSBURG, FL, USA - On September 23, 1970, the women who would become known as the WTA’s Original 9 signed $1 contracts to create professional women’s tennis - a moment that would change the sport forever.

To commemorate the 48th anniversary of that powerful event, the WTA hosted members of the Original 9 for a panel held at its world headquarters in St. Petersburg, Florida.

This year’s panel was formed by Billie Jean King, Peaches Bartkowicz and Rosie Casals who called in to share their thoughts and memories on the tour. They were moderated by two-time Grand Slam singles champion Mary Pierce.

King recalled moment when the WTA’s Original 9 famously held up their $1 bills, marking the start of women’s professional tennis.

The Original 9 hold up their $1 bills, a moment that marked the start of women's professional tennis. (1968)

“You’re going to think we were all smiling, giggly and happy, but deep down I think we were all - at least for me personally - I’m going, This is a real moment of truth for us because we may or may not make it, but I knew we were doing the right thing for the future generations and that’s really what we cared about,” King said.

In the summer of 1970, Jack Kramer’s prestigious Pacific Southwest event proposed paying the men more than eight times as much as the women - even though the intended women's field was packed with stars.

“This is a real moment of truth for us because we may or may not make it, but I knew we were doing the right thing for the future generations and that’s really what we cared about.”

- Billie Jean King

As a result, Gladys Heldman, the founder and publisher of World Tennis magazine, arranged for the Houston Racquet Club to host a women-only tournament. The event's initial $5,000 purse was to come from ticket sales to women's groups associated with tennis in the city. Heldman also persuaded her friend Joseph Cullman III, an avid tennis fan and chairman of tobacco giant Philip Morris, to provide an additional $2,500 - creating the Virginia Slims Invitational.

Read more: The women who changed tennis: Why the 'Original 9' matter to the WTA

Heldman recruited players who signed weeklong $1 contracts with her company. Despite threats from the United States Lawn Tennis Association (USLTA) that they would be banned from competing at Grand Slams and lose their national rankings, nine women signed up: King, Casals, Nancy Richey, Judy Dalton, Kerry Melville Reid, Julie Heldman, Kristy Pigeon, Peaches Bartkowicz and Valerie Ziegenfuss.

WTA CEO Steve Simon (left), Mary Pierce (center) and Peachy Kellmeyer (center right), along with the WTA's St. Petersburg office staff, recreate the Original 9's famous photograph. (WTA)

“It was a scary moment for us,” Casals recalled. “We really didn’t know what the future was going to bring but we knew that if we didn’t do anything about it, move forward and try to take risks, we wouldn’t have anything for sure. [The men] didn’t want the women as part of the tour and at that time we were part of the men’s tour.”

“We barely scraped eight people together to play [Houston],” Casals added, “But we had nine very heroic women who really took a chance and made a bold statement by taking that dollar bill, because that dollar bill… turned out to be multi-million.”

The success of the Houston event spawned into multiple women’s tennis tours until 1973, when they consolidated to form the Women’s Tennis Association, founded by King. For the first time, all of the top women would present a united front, and the tour hasn't looked back since: the 2018 edition of the WTA’s Race To Singapore travels through 54 events in more than 30 countries, and the WTA Finals Singapore features $7 million in prize money for the winner.

“We had nine very heroic women who really took a chance and made a bold statement by taking that dollar bill, because that dollar bill... turned out to be multi-million.”

- Rosie Casals

“I knew people would pay attention to us and for the future if I could make a $100,00 at that time,” King said. “People would say, Wow, they’re making that kind of money…  not just Billie Jean King, but [they all] are."

That prize money and sponsorship is more than just money in players’ pockets: the WTA funds the WTA Assistance Program (WTAAP), which provides physical, financial and psychological support and services for players - services that Bartkowicz credits with saving her life.

“I had a blood disorder and needed a bone marrow transplant. Dangerous option, but it was the only option to live,” she recalled. “Our Assistance Program provided the financial and emotional support. I can not thank WTAAP enough.”

King added: “It is important to think about today but also where do we want to take our sport, what do we want to do in the future to make the WTA better and stronger.”