Jackie Robinson broke baseball's color barrier in 1947. Arthur Ashe was the first African American to win the U.S. Open in 1968, but he didn't break tennis' color barrier. Althea Gibson had absolutely bulldozed that fence more than a decade earlier.

Billie Jean King would like you to know more about Althea Gibson.

"I guarantee you if she'd been a boy, there'd be a lot more attention," King said during a panel discussion celebrating the 45th anniversary of Title IX.

In 1950, Gibson became the first African American play in the U.S. National Championships, the precursor to the U.S. Open. A year later, she broke Wimbledon's color barrier.

In 1956, she became the first African American to win a Grand Slam, doing so at the French Open. She accomplished the same trailblazing task at Wimbledon and the U.S. Open in 1957, and she won both again in 1958. (She was runner-up in her lone appearance at the Australian Open in 1957.)

"Our first person, our Jackie Robinson was Althea Gibson," King said.

If that wasn't enough, after she was done with tennis, Gibson became the first African American to join the Ladies Professional Golf Association (LPGA).

The panel was part of the Sports Diversity & Inclusion Symposium that the USTA hosted at its Billie Jean King National Tennis Center. Good Morning America host Robin Roberts and USTA President Katrina Adams also participated.

After talking about Gibson, King got fired up about gender norms in sports.

"Another thing I cannot stand is when people say, 'Thanks for everything you did for women's tennis or what you did for women,'" King said. "Forget that. If a guy does something, they don't come up and say, 'Thanks for what you did for men.' What people do is keep the women's marketplace half as large.

"Women can be leaders, men are leaders, we all can be leaders. Everyone's an influencer. Every single one of us is an influencer. I think sometimes you forget that."

King won the U.S. Open in 1967, 1971, 1972 and 1974.

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