Serena Williams wasn’t raised to play tennis like everyone else.

Coached in relative isolation on the public courts of Compton, Calif., along with her older sister Venus, she learned the game from self-taught tennis parents who spurned the traditional junior circuit, believing their daughters’ performances one day would speak for themselves.

Throughout her 23-year pro career, Williams has done just that — winning 23 Grand Slam singles titles, which broke Steffi Graf’s Open era record, and four Olympic gold medals among an unprecedented trophy haul. She also redefined women’s tennis, ushering in a new era of power, athleticism and skill.

Along the way, she has spoken out when confronted with what she feels is injustice on the court — not always in the tone the sport traditionally expects of its female champions. She has pushed the boundaries with some officials and crossed the line with others, such as when she threatened to shove a ball down the throat of a line judge for calling a foot fault during a semifinal of the 2009 U.S. Open — a violation that cost her a point, the match and a record $82,500 fine.

Japan's Naomi Osaka held her trophy after beating her tennis idol, Serena Williams, in a dramatic U.S. Open final on Sept. 8. (Reuters)

Williams’s latest eruption came in the second set of Saturday’s U.S. Open final — a finger-pointing tirade at chair umpire Carlos Ramos that drew her third penalty of the match; cost her a game when she stood just two games from defeat to 20-year-old Naomi Osaka, who was by far the better and steadier player; and, on Sunday, resulted in a $17,000 fine.

After Williams’s rage subsided and the trophies were awarded — with Williams playing peacemaker, calling on the New York crowd to quit booing and celebrate Osaka, who wept through what should have been her shining moment following her 6-2, 6-4 triumph — Williams started an overdue conversation on two issues that tennis has dodged for too long:

●A rule book that is sorely in need of overhaul and capriciously applied — particularly on widely violated infractions such as foot faults and impermissible coaching. (It was a rarely called coaching violation that triggered the first strike against Williams on Saturday.)

●A double standard for men and women regarding on-court decorum, whether that’s Williams getting slapped with her third violation in Saturday’s final for berating Ramos and calling him a “thief” for docking her a point or French player Alizé Cornet being penalized earlier in the tournament for changing her shirt on-court under sweltering conditions — as is male players’ right. As Williams put it in her post-match interview: “I’ve seen other men call other umpires several things. I’m here fighting for women’s rights and for women’s equality and for all kinds of stuff. . . . He has never taken a game from a man because they said ‘thief.’ ”

Former champion Billie Jean King, who used her Hall of Fame career to advocate for equal rights, thanked Williams via social media for making the overdue point, tweeting: “When a woman is emotional, she’s ‘hysterical’ and she’s penalized for it. When a man does the same, he’s ‘outspoken’ & there are no repercussions. Thank you, @serenawilliams, for calling out this double standard. More voices are needed to do the same.”

Nearly 24 hours later, the Women’s Tennis Association acknowledged Williams’s point in a statement released Sunday night. “The WTA believes that there should be no difference in the standards of tolerance provided to the emotions expressed by men vs. women and is committed to working with the sport to ensure that all players are treated the same. We do not believe that this was done [Saturday] night.”

Williams is hardly without blame in the events that led to her one-game penalty, but neither is Ramos. As chair umpire, he had options to defuse what rapidly became an overheated situation and infuriated fans at Arthur Ashe Stadium. Instead of giving Williams what’s known as a “soft warning” after her second infraction (for racket abuse), he chose to apply the maximum penalty and dock her a game for what he deemed verbal abuse.

All told, it was a borderline circus in which both Ramos and Williams played bad actors and the tournament’s champion, Osaka, was robbed of well-deserved joy.

From this ugly incident, Williams can emerge a champion of a different sort — one who pushes the boundaries of her sport again by shining a light on a double standard that for decades has masqueraded as tradition and hidden behind words such a “respect” and “decorum.”

By calling out Ramos for penalizing her for language far less vulgar than profanities hurled at officials by Roger Federer and bad boys John McEnroe and Jimmy Connors before him, Williams has forced tennis to examine why it doesn’t accord women the same latitude as men to display raw, unvarnished and often ugly competitive fury as men.

“The sport definitely has a double standard when it comes to perception,” said former top-five player James Blake, 38, now tournament director of the Miami Open. “For example, women are vilified for speaking up when you look at the headlines; men can be considered ‘passionate’ or ‘fighters’ in similar situations. But I didn’t believe [the double standard] stretched to actual rules. That hope was dashed this U.S. Open when I saw the ruling against Cornet and then this happening to Serena.”

Blake went on to say in an email exchange Sunday that he wasn’t condoning bad behavior, noting that Williams deserved the second penalty for breaking her racket. But he characterized the verbal-abuse penalty as a “judgment call that was far too harsh and unnecessary.”

“If Carlos Ramos felt that she was taking it too far, he could easily say that as a warning and let her know that if she continued down that path, it would be a penalty,” Blake noted. “That’s a courtesy afforded to almost every pro but for some reason not to the greatest player of all time on the biggest stage? That’s concerning to me.”

Tennis has long had separate rules and expectations for women — most of which, throughout the sport’s history, have been proudly highlighted as matters of tradition.

There was no pay at all for victor Maud Watson in Wimbledon’s first event for ladies in 1884. She won a silver flower basket worth 20 guineas; her runner-up took home a silver mirror and brush set. While male players of the era wore slacks, women competed in long skirts and corsets.

The sport evolved, of course, with time and common sense.

But meaningful gains by women — particularly as it relates to equal pay — were demanded and earned rather than freely granted.

King, who earned 750 British pounds (roughly $969) for her 1968 Wimbledon singles title to Rod Laver’s 2,000 pounds (the equivalent of $2,584) for the men, started the campaign for equal pay. It was Venus Williams who delivered the compelling closing argument, via a 2006 editorial in the London Times, that persuaded Wimbledon to join the sport’s three other majors in awarding equal prize money the following year.

In other ways, Serena has been the force behind change in tennis.

Through the power of her groundstrokes and service blasts, she has forced her competitors to be stronger, faster, fitter and more skilled.

She has expanded notions of what female tennis champions look like and how they should dress — but only, as she explained in a 2016 interview with Common for ESPN’s the Undefeated, after learning to embrace her own muscular physique.

“There was a time when I didn’t feel incredibly comfortable about my body because I felt like I was too strong. I had to take a second and think: ‘Who says I’m too strong? This body has enabled me to be the greatest player that I can be,’ ” said Williams, who earlier this summer was criticized by French Tennis Federation officials for wearing a body-hugging leotard — it also served the medical purpose of preventing a recurrence of life-threatening blood clots — that they deemed “disrespectful” to the game.

Williams has evolved in other ways over her career, from 19-year-old U.S. Open champion focused on amassing more titles to 36-year-old, 23-time Grand Slam champion and mother who is trying, as an athlete, to speak to something larger about women. To push the boundaries of what is possible for new moms, all moms and all women striving to achieve on playing fields in which the rules are set by men.

It’s easy to take issue with her behavior in the U.S. Open final, destroying her racket, raging at the chair umpire and staging a tantrum that, intentionally or not, could have derailed a young opponent who had soundly outplayed her.

But tennis is better for her excellence, as the women’s final’s overnight TV ratings attest (up 32 percent from the 2017 U.S. Open women’s final, contested by Americans Sloane Stephens and Madison Keys, and 79 percent higher than the previous year, when Germany’s Angelique Kerber faced Czech Karolina Pliskova).

And in calling out the sport’s double standard on acceptable on-court passion (and rage), Williams makes a point that demands addressing.

Ava Wallace contributed from New York.