It's been 50 years since Billie Jean King's crusade for equal pay among male and female competitors in the US Open paid off.

Although King won the US Open women's singles title in 1972, she wasn't happy with her $10,000 paycheck. In contrast, her male counterpart Ilie Nastase won $25,000, per APNews.com's Brian Mahoney.

“I said, ‘This really stinks.' And, of course, deep down in my heart of hearts, in my brain, I'm going, ‘I haven't talked to them yet. You sure you're doing the right thing here? This is the other voice in my head: ‘What if they don't agree with you on this? I think they do, because we talk about it all the time, but we didn't talk about the move.' So I said, ‘The heck with it. I don't think we'll be back,'” King said on Thursday.

King threatened to boycott the 1973 US Open if her pleas for equal pay fell on deaf ears. Not only that, but her fellow female competitors would, too.

An irate Billie Jean King reached out to the biopharmaceutical company Bristol Myers Squibb. The firm helped cover the $15,000 discrepancy in prize money.

Thanks to King's efforts, the 1973 US Open eventually became the first sports event that paid male and female participants the same. Tournament organizers will celebrate the 50th anniversary of that epic milestone next month. They will host the festivities during the US Open Grand Slam at the USTA Billie Jean National Tennis Center in Queens, NY.

The winners of the 2023 US Open will receive $3 million each in prize money. Spain's Carlos Alcaraz recently became the tournament's youngest No. seed. On the other hand, Poland's Iga Swiatek is the No. 1 seed in the women's division.

The US Open has certainly come a long way since Billie Jean King took an important stand 50 years ago.