This was as close as Steffi Graf came to losing at a major in 1988: Returning at 15-15, down a set and a break to the no. 2 seed, the 18-time slam champion Martina Navratilova, Graf stepped inside the baseline, pounced on a serve out wide, and, with a scything forehand, sent the ball into the far corner for a winner. On the next point, Navratilova served and volleyed, stretching to reach a cross-court return and somehow blocking it over the net. The ball would have bounced twice against anyone else, but Graf was already creeping toward the net. She accelerated automatically, astonishingly, and reached the ball with time to bat it easily into the open court. After a fierce squint and another leaping forehand return, the break was hers. She walked to her chair without a smile. Graf would win the rest of the games in that set and then take the third 6-1.

Entering that Wimbledon final against Navratilova, Graf had lost only 17 total games in the entire tournament. That first set was the first she had lost in any major that year. For other players, moral victories were measured not in games but points. “For a while there, I felt very naked,” no. 3 seed Pam Shriver said after losing her semifinal match to Graf 6-1, 6-2 in under an hour.

Graf finished her career with 22 major titles, the most of any player in the Open era. She won 107 titles overall and 900 matches; she spent a record 377 weeks at the top of the rankings. She won every slam at least four times. But it is the period of dominance from 1987 to 1990 — including that 1988 grand slam, when she won all four majors (plus the Olympic gold) — early in her career that sets her apart. And it is the period of dominance that followed the stabbing of Monica Seles in 1993 that has made her career harder to assess.

She won simply, without drama. She was brilliant without being blazing. She was merely the best.

♦♦♦

She was described the way one would a German engine, precise and powerful and well designed, known for her balance, her agility, and above all her forehand drive. She had the kind of game that people liked to break down, to treat as machinery and parts. It began with the feet: her footwork, intricate and efficient. Her speed and homing instinct, her capacity to go from standing to a sprint before a drop shot was dropped. Her serve, a high toss and heavy hammer. Her versatility, her effectiveness on every surface. Her clinical strokes, better than classic — the skidding slice backhand, the proficient volley, and the forehand that changed the game. The heat emanating from the engine of her determination was an intensely cool blue.

Rarely did anyone talk about her animating genius, even though she had a fingertip feel for the game and an artist’s way of fingerprinting her form. She was held at a distance and held herself there, too. She rarely looked emotional. Winning was a matter of routine. She almost never lost.

She started playing tennis at the age of 3, after her father, Peter, a car and insurance salesman, sawed off the end of a racket and taught her to swing it in the living room of her West German home. She and her father used the couch as a net, and he rewarded her with ice cream for rallying for 25 shots. “Most of the time,” Peter Graf later said, “on the 25th ball, I would hit it too hard or so she could not return it, because you cannot have ice cream all the time.” By 5, she was winning tournaments. She turned pro at the age of 13.

Even after her father ceded her tennis to a coach, he controlled her schedule, her commitments, her friendships. (There were none.) “I think only of tennis, tennis, tennis,” she is quoted as saying in a biography. And it worked. Her rise was meteoric, but she never flamed out. She was 16 the first time she beat Chris Evert and Navratilova, 17 when she won her first major, and 18 when she became no. 1. She turned 19 the summer of the year that would define her dominance of the sport.

“Her emotions seem to run the gamut from A to B: apathy to boredom,” wrote Sports Illustrated after she won the 1988 U.S. Open to complete the calendar slam.

We knew her as Steffi Graf. She thought of herself as Stefanie.

♦♦♦

At this year’s U.S. Open, which begins Monday, Serena Williams will have the chance to equal Graf’s record for major titles and become the first player to win the calendar slam since Graf did it in 1988. If Serena does, it will be more than a triumph; it will be a coronation. Which is as it should be. For her longevity, for her skill, for her ability to will herself to win when she is down, for her record against any would-be rival, for the way she has transformed the sport, she deserves the attention she gets, and more. But it’s a mistake to recall Graf’s calendar slam — or “Golden Slam,” with the Olympic gold included — as just a reference point. There are different ways to dominate.

When she did it, Graf changed the game. She beat contemporaries and legends, serve-and-volleyers and baseliners, clay-court specialists and Wimbledon champs. She played a new kind of game, overpowering and versatile and fast. “Navratilova looks absolutely old-fashioned,” wrote the L.A. Times before the 1988 Wimbledon final. In the final of the Australian Open that year, Evert, a baseliner who won 18 major titles and spent 260 weeks ranked no. 1, seemed to stand still while Graf moved and flowed.

There were no answers for her. At Roland Garros, she lost a total of 20 games in the entire tournament. “We had played only one game,” said Graf’s second-round opponent, Janine Thompson, “when I asked myself ‘What the hell am I going to do?’” In the final, Graf beat Natasha Zvereva 6-0, 6-0 in 32 minutes — again, 6-0, 6-0 in 32 minutes, in the final of a major. It was the fastest match ever at Roland Garros and the first time a French Open finalist had failed to win a single game.

Coming into the U.S. Open, Graf faced an unprecedented challenge. No one had ever won the calendar slam on three different surfaces (clay, grass, and hard court), and no player had won it in 18 years. Graf handled the pressure the way fire handles ice. There was a momentary wavering in the U.S. Open final when Gabriela Sabatini tried to fool Graf with offspeed deep shots, but Graf adjusted. She won the third set 6-1.

Afterward, instead of joy, she expressed relief. “There’s nothing else people can tell me I have to do,” she said.

Her father refused to let her attend that year’s Women’s International Tennis Association banquet, where she would be honored as player of the year, until the organizers could guarantee she would be in bed by 9 p.m.

♦♦♦

There were attempts to soften her image — magazine spreads in which she wore pretty dresses, profiles that insisted on her shy giggle and signs of sweetness. But these stories came across as stagy and managed — and they were, usually by her father, who taught her to swing, coached her for years, controlled her time and relationships and finances for longer.

Some scenes in those profiles now seem creepy, however they read at the time. From the L.A. Times, in 1987, when Graf was 18 and newly no. 1:

“When she finds someone, he must be a tennis player or a sportsman I think,” [Peter Graf] said. “If it is not, it will be difficult for him to understand her love of tennis.” As the father talked, the daughter walked in, your basic 18-year-old. She wore faded blue jeans and a striped shirt. In one hand she carried sunglasses; in the other, an audio set. She was on her way into Manhattan to buy a birthday present for her brother, who recently turned 16. “I’m taking him with me to choose,” she said, laughing. “It’s much easier that way.” She sat down next to her father, who patted her on the knee affectionately. “No husband for you, right?” he said with a grin. “Not so long as I am your father.” Steffi Graf rolled her eyes. “OK, I tell you what,” Peter Graf said. “You can have a husband … in the next life.” Steffi Graf laughed, clearly comfortable when her father teases her. “He is the one who takes the pressure off me,” she said. “People do not get angry with me. They get angry with him.”

The man she did marry was a tennis player, Andre Agassi. They got together shortly after both of them won the French Open and both of them lost the Wimbledon final in 1999. In his memoir, Open, Agassi describes one of their early dates, at the beach. “We talk for the first time about tennis,” Agassi wrote. “When I tell her that I hate it, she turns to me with a look that says, Of course. Doesn’t everyone?”

♦♦♦

Her run continued. The year after winning the calendar slam, Graf would go 86-2. She would win three of four majors, during a run of 13 consecutive slam finals. Between 1989 and 1990, she won 11 straight titles. She was peerless.

Until, quite suddenly, she wasn’t. In Berlin in 1990, her 66-match winning streak ended. Then she lost the French Open. After Berlin, she took her racket and smashed a hole in the wall of the locker room. After Roland Garros, she cried.

Off the court, her struggles played out in public. Her father was facing a paternity suit from a former Playboy model; he was on the cover of German tabloids for two months. Graf was clearly rattled, hounded by the press. She struggled with injuries. And she struggled even more with the woman who beat her in those two 1990 matches, a player with unconventional two-handed attacking strokes and a mentality that was unmatched.

Monica Seles took the ball early and hit it hard. She would win seven of nine majors between 1991 and 1993 and supplant Graf at no. 1. (Graf won the other two, both Wimbledons.) Their battles were tight, but the edge was decisive. Seles could outhit Graf from the baseline — and she could get into Graf’s head. At the final in Roland Garros in 1992, Graf saved six match points before losing 10-8 in the third set. At the final of the Australian Open the following year, the two played a tremendously high-quality three-set match, striking lines and ending points on winners. But Seles had the air that Graf once did: invincibility.

Then came one of the most horrific events any sport has ever seen, the stabbing of Seles on court by an insane fan in Hamburg, Germany, in 1993. He did it in Graf’s name. (It wasn’t the first time an obsessive fan had stalked Graf. Another one had scaled a fence to get onto her court and slit his wrists in her presence after she refused to marry him.) Seles missed 27 months; when she came back, she wasn’t quite the same. Graf quickly reclaimed the top ranking. But she attached an asterisk to the rest of her career herself.

What if? It was a grotesque question in light of what happened. “I know it took away from the sport, but foremost I think about what happened to Monica and the tragedy of her having to deal with that,” Graf told ESPN’s Melissa Isaacson earlier this year. “Everybody was worse off — the fans, myself, no question missing her, missing the possible matches we would have had that didn’t happen … I cared for her as a person, and looking back, yes, it was horrible for the sport, but what happened to her was a tragedy.”

Who cares about tennis? But tennis had been her life.

Graf kept playing. She kept winning. She won 10 of the next 15 majors. Three years after that stretch, she won the 1999 French Open and made the finals of Wimbledon, where she lost to Lindsay Davenport.

Then, abruptly, she retired. She was 30 years old, still the third-ranked player in the world.

♦♦♦

“If you could ask [Graf] one thing heading into the U.S. Open, what might that be?” Serena Williams was asked in Cincinnati last week.

“Well, I would just ask her what does it feel like, just in case it doesn’t happen?” she answered to laughter.

Graf was asked a similar question just after winning. Was it the greatest day of her life? “It’s hard to say,” she answered. “It needs some time. The next couple of days will be good.”

♦♦♦

History is the territory of those who protect their legacy. Graf let it go. She moved to Las Vegas, married Agassi, became the mother of a daughter and a son. She started a charity, Children for Tomorrow, working with children traumatized by war.

She gives the occasional interview, insisting on her happiness as a mother, as a wife, but for the most part she avoids the press. She didn’t disappear entirely. She posts pictures of hamsters and Little League fields on social media. She makes money, has endorsements, plays the occasional exhibition. She and Agassi showed up ringside at Mayweather-Pacquiao in May. Together they made terrible watch commercials. Occasionally, German players would fly to the desert to hit with her. They often came away talking about those sessions as turning points. When they’d ask her to be their coach, she’d say no. She follows tennis, she told Isaacson, “from a real distance.” When the WTA celebrated its 40th anniversary, she did not attend. Other top players have kept themselves in the spotlight as television commentators and coaches. Graf has done little to protect, let alone promote, her legacy. But it isn’t quite humility that she projects. It’s something more painful and shy.

When Agassi introduced Graf at her Hall of Fame induction ceremony in 2004, he compared her to a cathedral, perfect in every unseen corner, every crack. “You never need applause to be at your best, you only need to give the best your soul could give to feel complete … You have always been about action, not about words. You have never defined yourself by what you’ve achieved; rather you have achieved all that you have because of how you have defined yourself. Even now it takes my breath away seeing how you quietly laid down your racket to pursue love and motherhood with the same zeal and high standards you have always demanded of yourself.”

From a very great distance, she seems happy. It’s tempting to say that we know her better now. We, too, know her not just as Steffi Graf but as Stefanie. Except that a cathedral is no less a thing than a German machine.