Their rivalry, which coincided with the emergence of multimillion-dollar corporate sports sponsorship deals, would help elevate the newly founded WTA.

Women’s professional tennis had begun in 1970 when King and eight other women, known as “The Original 9,” signed $1 contracts with the World Tennis magazine publisher Gladys Heldman as they tried to establish their own tour because existing events paid women a fraction of what the men earned.

A year later, the Virginia Slims Series started with 19 tournaments and total prize money of $309,100. King founded the WTA in 1973, and by 1980 more than 250 women played tennis for a living on a tour that had dozens of events around the world, with $7.2 million in prize money, according to the WTA.

With the WTA experiencing such rapid growth in the 1970s, some tough decisions had to be made.

In April 1978, the WTA board decided not to extend its long-term sponsorship with the tobacco company Philip Morris, whose Virginia Slims brand had bankrolled the women’s tour from its early beginnings in 1970, according to “Women’s Tennis 1968-1984: The Ultimate Guide” by John Dolan.

The move, driven partly by the introduction of antismoking legislation in advertising in the United States and a desire for more flexibility in tournament draw sizes and prize money structure, was controversial at the time. But three months later, the WTA announced a $2.2 million deal with Avon Cosmetics for 1979.

For the 21-year-old Carillo, 1978 would also be a transformative year.

Carillo was 16 when she watched on TV as King beat Bobby Riggs in the 1973 “Battle of Sexes.”

“It was one of the great affirming moments of my life,” Carillo said. “There was such noise about that match in the weeks before. I couldn’t believe she was able to pull that off, and in straight sets.”