There are so many sides to Serena Williams. Slick and powerful in heels and leotard, she dances, squats and bounces beside Beyoncé in the video for Sorry. She has been lauded by Claudia Rankine, whose award-winning, book-length poem Citizen last year depicted Williams “as hemmed in as any other black body thrown against our American background”. She is the world’s top-earning female athlete. And arguably more than any of her contemporaries, her body has been the focus, the point of intersection, of so many arguments about femininity, power and race that it would almost be possible to overlook the tennis.

But the tennis, of course, is unforgettable. Williams has won 21 grand slams. One more – next week at Wimbledon, say – would bring her level with Steffi Graf’s total, and only two short of Margaret Court’s all-time record of 24. Williams has been playing since she was three. In September, she turns 35. If she stays fit, if the strength holds, if she keeps winning, if young rivals prosper temperately, maybe she can hurl herself through the narrowing gap of time to leave a new number in the record books. But meanwhile, she is singing karaoke at a pre-tournament party. When a TV interviewer points out that a strap of her crop top has slipped, she gives her shoulder a brief glance. “Yeah,” she says. “I know.” Through everything, she is a self-stylist.

How did you get involved with Beyoncé’s album Lemonade?

We’ve known each other a really long time. I’ve known the director [Dikayl Rimmasch] since he was nine. My lawyer – it’s his son. We kind of grew up together. They were like, “It would be good for Serena.” Beyoncé had so many inspirational women in that part, in her documentary video. She says she loves when I dance cos I dance like no one’s watching. I’m like, “Oh, but that’s different cos there’s no cameras, there’s no one watching.” But, yeah, that’s kind of what I was trying to do. It worked out good. She had a lot of people. She had Trayvon Martin’s mother, Michael Brown’s [mother] as well, the victims of that horrible violence we are seeing in the United States, as well as some beautiful ballerinas, body-imaging women who really love themselves and embrace themselves, so other people embrace them, too. It was really powerful putting African-American women together in her story, because she’s obviously a super strong African-American woman.

Did she explain it to you in those terms?

She explained it to me in different terms, but we kind of have a similar take on a lot of things. She’s gone through so much and been so positive.

Some people argue that only African-American women can truly relate to Lemonade …

No! I think women in general can relate to it. I think it was a powerful piece for everybody, I think it definitely, 100% crossed colour boundaries. Absolutely.

Did you and Beyoncé discuss some of the themes – infidelity, for instance?

Oh God, no. No, that’s not my … I don’t know about that. It was just getting together with strong women.

Over the years, your body has been described and criticised repeatedly. Why do you think people have felt so free to comment?

I guess it’s a part of being in the public eye. You have to accept that people are going to have a say, whether it’s your body, or your face, or your hands. It could be your feet. Nothing is off limits. I think that’s why, growing up, my mum – not consciously, subconsciously – taught myself and all my sisters to be so strong. It prepared me for these moments.

Did she do that particularly with regard to body shape?

A little bit. Also my older sister, too. But she always taught us to love ourselves and I think that is a wonderful message that I spread now to so many females. It’s really important. You are who you are, you can’t change it. And you’re beautiful.

Do the comments still hurt, or did you stop listening?

For every negative comment, there’s a million good comments. I always say, “Not everyone’s going to like the way I look.” Everyone has different types. If we all liked the same thing, it would make the world a really boring place! What matters most is that I like myself.

Right. Because you’ve been described as too muscular, too feminine …

Too muscly and too masculine, and then a week later too racy and too sexy. So for me it was just really a big joke.

Have you thought about growing your eyebrows very, very long just to show people that you get to decide?

No, it’s fine. I find it really funny. Sometimes it’s true. I’m like, “Gosh, I need to shape these brows!” Can’t argue with the truth sometimes!

You have triumphed in a white-male-dominated world without compromising who you are. Do you feel you have fought for black women everywhere?

I do, but I feel it’s for all women everywhere. I have so many different people, races and colours who can relate with my story, whether they’re poor or rich or middle class, it doesn’t matter. My goal is to inspire every woman out there. My new saying for the past few years has been: “The success of one woman should be the inspiration for the next.” And by the way, it’s great for your health and it keeps young women and girls out of trouble.

This job of inspiring or representing others – does it sometimes feel like a duty or a burden?

I don’t see it as a responsibility and a duty, but I embrace it because I am who I am. I feel I can give that message because I’m living that message. Does that make sense? I embrace it and I love that I have an opportunity to do it because a lot of people don’t. And I don’t have to be anyone different, cos this is me. And it really fits well with me.

Claudia Rankine included a long section about you in her brilliant poem Citizen. Was that a surprise?

Totally. She interviewed me, too. Her piece [on black excellence, for the New York Times] was one of the best things I’ve read. It wasn’t about a story, it was just about the truth. And that poem, with me in it – it was so powerful. I love her work.

Rankine’s poem refers to the mistaken decisions by umpire Mariana Alves at the US Open in 2004, which contributed to your early exit from the tournament. It includes the line: “Though no one was saying anything explicitly about Serena’s black body, you are not the only viewer who thought it was getting in the way of Alves’ sightline …” Did that resonate with you?

I just felt it was very true. And that’s why I liked the story [on black excellence], too. It was just things that are true. There’s fact and there’s reality, and there’s fiction and what she said, she just said facts. Those are simple facts.

Was there anything in particular that stood out, where you felt she nailed it?

That line you gave is a great example, but there’s a lot of stuff. Besides all that, she’s a really inspiring writer.

You said that your dad describes you as a good daughter, and one day you hope to have good children, too. Is having kids on your mind?

It is, it is. It is something I think about a lot, especially now. But I think everything will be OK. I have a feeling that everything is going to work out, and I don’t think I am done with what I am supposed to do yet. I just don’t feel it’s time, and I think when it is time, everything will work out.

And will you know when it’s time?

Yeah, I think I’ll know. I know I’ll know. I’ve been intuitive my whole life. I just think when everything is done and said, I’ll have a great feeling, and I’ll have a great life, I hope.

Do you have a number of grand slams in your head that you want to reach before you allow yourself to retire?

No. I never even thought, at 21, I would be here. I don’t think anyone thinks about it. I mean, maybe some people do, but I didn’t. I don’t have a number. I’m just relying on a feeling. A good old feeling.