The former world number one was talking to actress Natalie Portman as part of the launch of Angel FC, a new American professional women's soccer team.
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Asked about the long fight for equality, Williams said she was used to asking for parity in representation between the sexes, and also within her own sport of women's tennis.
"That's something we have to fight for still in tennis," she said.
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"I'll look at the schedule and there's four men's matches and then two women's matches and then I feel bad, because I'm always one of those women.
"I literally have said just put me on the second court, so we can have other players have an opportunity on centre court.
"Obviously that doesn't go well in the timings, and they're like, 'No, no, no. You need be on centre court,' and I'm like, 'These other women need a chance and they deserve it, they've been working literally their whole lives to have this opportunity.'"
Williams also told Portman that she saw little progress when she returned to previous events.
"Every year I come back to the same tournaments and I come back with the same arguments. They expect me, so when are we going to make those changes?"
Williams is set to compete in 2020's US Open tournament, starting on 31 August.
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