The Original 9 are the nine players who signed $1 contracts with World Tennis publications publisher Gladys Heldman in 1970 to compete in what would become the Virginia Slims Series, signifying the launch of women's professional tennis. They were Billie Jean King, Rosie Casals, Nancy Richey, Kerry Melville, Peaches Bartkowicz, Kristy Pigeon, Judy Dalton, Valerie Ziegenfuss and Julie Heldman.
"I think we can't thank them enough," Petkovic said. "I'm a huge feminist myself and I really believe in the independence of women and the strength and the power of women, not women's tennis, but women in general. I am so grateful that there were these women before us that fought the fight for us and we're having this comfortable life and sort of sitting in a bed that's been already made for us. The only thing that I can do is just appreciate it and thank them every time I see them. I just feel huge respect when I see Billie Jean King and the others.
"For me it's just a thing of gratefulness and admiring them and looking at them as role models who took a different path. They made me realize that things can change, and that's very inspiring."
Petkovic said there are still battles for women's tennis players to fight.
"I don't think there's ever going to be an end to this story," Petkovic said. "I think it's just a consistent journey that is there and that we have to indulge in each day. I get it that the men are bigger stars, but then again, Maria and Serena and Venus, they are cross-over pop stars, and I think it's just a matter of taking the attention and not being afraid of taking the attention and being proud of the attention that we get. I think the girls do an amazing job every day, and they fight their hearts out.
"So I think there is still a lot to be done, but then again, we are trying every day to be good role models and idols for the little girls out there."
Petkovic went on to win the 2014 Family Circle Cup for her first WTA title in almost three years.
At its maiden staging in Hilton Head in 1973, the Family Circle Cup was the first women's tennis tournament to offer $100,000 in prize money and the first to be broadcast on network television. It moved to Amelia Island in 1975, back to Hilton Head in 1977 and settled in its current home of Charleston in 2001. The Original 9 reunited at the Family Circle Cup's 40th anniversary in April 2012, when the stadium court was named after King.