Venus Williams has tuned out all manner of distractions on her way to becoming one of the most successful women to set foot on a tennis court. But on a recent June morning in downtown New York City, there was no competing with the doe eyes of her 11-year-old Havanese, Harry, as he peeked his head out of her backpack. “Hi, good morning again,” Williams cooed as she buried her face in Harry’s fur. “You’re awful cute, aren’t you?”

As Harry gazes at her, Williams snaps back to attention and explains why, at age 38, with seven major tournament titles, a successful clothing brand and an interior-design business to her name, she keeps grinding away on the tennis tour. “I think you see some players, they’re clearly not playing well and they can’t keep up and they just can’t compete,” Williams says. “This is not a problem that I have.”

Williams is putting it modestly. More than two decades after her pro debut and seven years after being diagnosed with Sjögren’s syndrome, an autoimmune disorder that causes pain and fatigue, Williams is still among the game’s elite. In 2017 she reached the final of two Grand Slam tournaments and a semifinal of a third. This season has been rougher–she fell in the first round at both the Australian and French Opens. But if history is any guide, Wimbledon, which starts on July 2, could be the antidote.

The manicured grass of the All England Club has been particularly kind to Williams. Aided by her knack for running down balls on the fast surface that sneak past other players, she has won the singles title five times and, paired with sister Serena, the doubles title six times. (“Those titles count,” Williams says, smiling.) Those matches included some of the most memorable in recent history, including the three-set classic over Lindsay Davenport in the 2005 final and her straight-set triumph over Serena in ’08. Last July, Williams became the oldest Wimbledon finalist since Martina Navratilova in 1994.

Wimbledon is significant for another reason: it’s where Williams took a stand for equal prize money that helped the women achieve pay parity with the men. The day before she won the 2005 title, Williams addressed the Grand Slam Board, made up of executives from the four major events, in the boardroom at the august All England Lawn Tennis and Croquet Club. At that time, only the U.S. Open and the Australian Open offered equal prize money for men and women; Wimbledon and the French Open were still holding out. She gazed at the tennis pooh-bahs and asked them to close their eyes and follow her on a thought experiment. “You feel like you’re going against people who maybe have made up their minds already,” Williams says, recalling the moment. “I felt like I had to say something that was very humanizing because these people on the board, they have mothers, they have daughters, they have sisters. They have to remember that these women who are not getting equal prize money are mothers and daughters and sisters. You have to look at it that way, or else you might not be able to see through it.”

In April 2006, the French Open announced it would close its pay gap and offer both champions the same prize money. Wimbledon, however, stood firm. So Williams took her crusade public, writing in a June 2006 op-ed in the Times of London: “I feel so strongly that Wimbledon’s stance devalues the principle of meritocracy and diminishes the years of hard work that women on the tour have put into becoming professional tennis players.”

Williams’ crusade helped convince British Parliament to take up the issue. Prime Minister Tony Blair called for equal prize money. In early 2007, Wimbledon changed its policy. “It all happened so quickly,” Williams says. “We all thought we were going to fight for a lot more years.” This year the men’s and women’s champions will each earn around $3 million.

The debate, however, still rears its head. Rafael Nadal, who won his 11th French Open title in June, recently suggested that there can be reasons for pay disparities in a field. “Female models earn more than male models and nobody says anything,” Nadal told an Italian magazine. “Why? Because they have a larger following. In tennis too, who gathers a larger audience earns more.” When I read Nadal’s comments to Williams, she declined to return serve. “I don’t know anything about modeling,” she says. “I guess that’s a metaphor that makes sense to him.”

Williams is well aware that the pay gap is far from closed outside of tennis. American women earn 80¢ for every dollar taken home by men. “There’s still a lot of work to be done,” says Williams. “But men have to want it just as much as women. That’s very important. We have to raise our sons in a way that that we see women as equals.”

Looking back on the push for equal pay, Williams says she is an unlikely trailblazer. “I’m not necessarily a person who’s looking to be a leader in the middle of a crowd,” she says. “My job puts me in the middle of the crowd, but it’s not really how I live my life. But I’m also the kind of person that if you start a fight with me, then trust me, I’m going to end it. Don’t start anything with me.”

A decade ago, few would have wagered that the Venus and Serena would still be playing competitive tennis, let alone thriving in tournaments. They were rare talents, sure, but critics said the sisters had too many outside interests. And many wondered how Williams would be able to continue to play at the top level after her Sjögren’s-syndrome diagnosis. Williams did explore life beyond the court. She earned degrees in business and fashion design. “Not being more than an athlete was considered a failure in my household,” she says.

But it turns out that in refusing to pile up on tournament appearances in their 20s, the Williams sisters were able to flourish into their 30s. “It’s about planning a smart schedule,” says Williams. “A lot of people didn’t do that. Mental burnout is just as bad as physical burnout. Maybe worse.”

At last year’s Wimbledon, Williams broke down in tears after a reporter asked her about a incident that had occurred weeks earlier, when she was involved in a car accident in Florida that took the life of another car’s passenger. In December, police cleared Williams of any criminal wrongdoing. The deceased man’s family has filed a wrongful-death lawsuit against Williams, who declined to talk to TIME about the case.

Pundits have written millions of words, and filled hours of airtime, explaining the meaning of the sisters to their sport, and society at large. Williams is far less inclined to do the same. Asked how she would describe her impact, Williams deflects introspection like an errant ball. “Oh my gosh, I have to work on my wide serve,” Williams says. “Why am I not moving faster? Those are the things I think about. I don’t sit back and reminisce on any achievement, because that’s the past. And I don’t live in the past.”

This appears in the July 02, 2018 issue of TIME.

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Write to Sean Gregory at sean.gregory@time.com.