Someday, perhaps even someday soon, when we have forgotten what the record books can’t tell us, we may remember only that Venus Williams was there. If Serena Williams wins the U.S. Open title — and it is becoming harder to imagine she won’t — then Venus will be another name in the column of players Serena defeated on her march to history — a singular name, certainly for what it shares with the winner, but still only a name.

This is the way records work, after all: They erase what went into them. And so history will record that Serena Williams defeated Venus Williams 6-2, 1-6, 6-3 in the quarterfinals of the 2015 U.S. Open. Trivia will give us more: the combined age of the opponents (68); their combined Grand Slam titles (29). The stats will tell us the speeds of serves, the numbers of winners and errors, the differences in approach to net.

S. Williams d. V. Williams. We won’t think of the way Venus stretched for flat wide serves, or swung her volley to bat back passing shots, or hit flat forehands that skimmed the net and struck the backs of lines. We won’t know how many times she drove the ball with such strength and pace that it knocked Serena onto her heels — nor, playing the greatest defensive player in the game, how many of those points Venus still lost.

It was a strange match, both better and wilder than most (including me) predicted it would be. There were tight holds to begin, as Venus moved to cut points short and Serena played patiently to stay in them and then win them. In the second, Serena’s clean hitting gave way to baffling errors. Venus went for first-strike forehands and then streamed forward after striking them. Serena baited Venus with short balls and then slipped the ball by. Both cut sharp angles out of sharp angles; both snuck well inside the baseline to return. And finally, a close but inexorable third set, as Serena did what she so rarely does against her sister: clenched her fist, crouched, and roared.

“She’s fast; I’m fast. She hits hard; I hit hard. She serves big; I serve big,” Serena said before the match. “We have a very similar game. We had the same coach for a long time. It’s like playing a mirror.” Which was true, to a point — watch their open backhands and you’ll see their shared parentage — but there are big differences in the way they approached points, and key differences in points that mattered: more loose groundstrokes from Venus, and, crucially, a weaker second serve. And there was the big difference of the emotional temperaments on the court: Venus’s desperate intensity and passive expressions; Serena’s patient movements and riling joy and fury. “Come on!” she’d yell in a way that would make me run.

On match point, Serena hit a serve that Venus couldn’t touch.

Serena advanced, Venus was here. And that is the strange and singular story of Venus’s remarkable and too much forgotten career.

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It was not her moment. It has not been her moment for some time. Venus Williams has had many memorable experiences, has raised trophies and graced magazine covers, is famous in her own right. But it has been a long time since people looked at the draw and traced her path to the finals. For the past few years, she has sat in mostly empty interview rooms, looking drowsily, speaking guardedly, smiling graciously at the handful of reporters who ask her about her health and, inevitably, about her sister. When she goes on a run, when she wins a tournament — it still happens — admiring stories will appear, applauding her courage and resilience and longevity and grace, as they should, because, really, what a story. Venus Williams, 35 years old, suffering from an autoimmune disorder, is capable of playing some of the best tennis in the world on any given day, even if sometimes it’s hard to get out of bed on any other. For the past four years, ever since she withdrew from the 2011 U.S. Open and announced that she was suffering from Sjögren’s syndrome, her success has been judged in relative terms. Isn’t it amazing what she can do — considering?

That is a story about surviving — about being there. It is a story that tacitly suggests that winning isn’t everything, which is another way of acknowledging that winning is now rare. Only one woman can win. It is a little different, of course, when you have been a great champion yourself, and when the one who wins was once your rival, and when the woman who once was your rival is your little sister. It is a little different for Venus Williams. But it is always different for Venus Williams.

Clive Brunskill/Allsport Venus and Serena at a tournament in Germany in 1999.

She was born to be great; her sister was born to be greatest. This is part of the legend, the Gospel according to Richard. Serena would be better, he liked to tell people who noticed Venus, who were awed by the way a skinny child with preternatural grace could bash the ball. And Richard, the prophet, the progenitor, the Prospero, was right.

It wasn’t quite that simple, of course; at least at first, Venus often won. (Serena still leads their head-to-head 16-11 — which is about as close as Serena’s head-to-heads get.) The matches were weird; occasionally thrilling but sometimes tense and awkward. In the beginning, there were rumors that Richard had fixed the outcomes; these were ugly and baseless insinuations, but there was certainly some psychological rigging. Imagine what it would have been like to compete against your sister, your training partner, your friend, your mirror, with the expectation that you would be fighting each other for supremacy of the world — and now stop, because you can’t.

“I think she helped create me,” Serena said earlier this week when asked about her sister.

Venus was protective, guarded. The older sister who would drape an arm across the shoulder, who let the younger one giggle and whine. Venus was the one who went through the brutal business of breaking into a closed, mostly white world — the one who was bumped, intentionally, by another player, Irina Spirlea, on a changeover (“She thinks she’s the fucking Venus Williams!” Spirlea had said with a grin), and who sat through a press conference so racially charged that she begged for the questions to stop at the 1997 U.S. Open, where she had reached the final as a 66th-ranked 17-year-old. She is the political one, the one who fought for equal pay. She was the one whose withdrawal at Indian Wells sparked the booing. She is the one who hasn’t gone back.

She was accepted, in some ways more quickly, for the old reasons: She was slender, gracious, so obviously pretty. But she held herself back more, too. Another way of looking at this is that she kept a little of her life in reserve. While Serena was chasing more history this summer, Venus was walking at graduation to receive her business degree from Indiana University East — and working with the school and the WTA Players’ Council to set up a program to make sure other players could, too.

If the meaning of Serena is the freedom to be Serena, it is partly because Venus came first.

And if Serena won, it’s because Venus lost. They played each other in four consecutive Slam finals. Venus lost them all. It was the first Serena Slam.

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At the end of the match, Serena, who had become emotional — focused, competitive, angry — as the match went on, began a celebration, then quickly tamped it down. She approached the net looking tired and subdued. At the net, Venus wrapped both arms around her, smiled, and whispered in her ear. She exuded the kind of happiness that can’t be feigned.

The stats flashed on the JumboTron. In the end, Serena won 76 points during the match. Venus won 75.

Venus always seemed to hold herself a little bit apart, a little reserved. She was a mystery to me, an enigma. I called her a vanishing act. I used to wonder why she played. It seems like a silly and regrettable question now. She is still here — vividly, emphatically.

When I think of her now, I think of the moment before she serves. She pauses, looks inward, looks up. The world is reduced to a spinning ball. Then those long, loose limbs let fly and she rears.