Monday night’s presidential debate was always going to be a battle of the sexes—the political version of the epic 1973 tennis showdown between Billie Jean King and Bobby Riggs. The first female presidential nominee was debating a candidate who has called women “dogs” and “slobs,” who bragged about his testosterone score on Dr. Oz and talked about his private parts at a Republican primary debate.

But the fight between Hillary Clinton and Donald Trump was not fought on such overt terms at Hofstra University on Monday. On the surface, the two sparred over ISIS and crime and nuclear weapons and trade deals. But between the lines, the debate was fought in glares, eye rolls and interruptions.

From the beginning, the debate conformed to classic gender stereotypes. Clinton has been preparing for days, hunkered down with briefing books and rotating through several different stand-ins for her opponent, while Trump had reportedly barely studied, preferring instead to wing it. That’s consistent with research that shows that women tend to over-prepare while men tend to have more confidence, a trend that starts in elementary school, where girls do more homework and get better grades than boys.

Clinton started out by putting women’s issues front-and-center. She emphasized child care, paid family leave, and equal pay in her opening statement, all issues that have never gotten much airtime in presidential elections dominated by male candidates. For Clinton, they’re an essential part of her stump speech, as central to her campaign as the border wall is to Trump’s.

Throughout the 90-minute debate, Trump exercised all the subtle put-downs familiar to almost any woman who has sat through a business meeting with a dismissive man. He sighed loudly and rolled his eyes while Clinton spoke. He interrupted Clinton more than 50 times, according to some estimates. At one point, he leaned down to this microphone and said “wrong, wrong wrong” during her answer. Another time, after she tried to respond to a lengthly explanation of her own alleged failings to bring back jobs, Trump put up his hand and said “excuse me” and continued to speak until Clinton finally interjected to note that, Finally, Clinton was able to say, “well actually, I have thought about this quite a bit.”

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Clinton also did her part to put Trump on edge. She began the debate by calling him Donald, even though he insists most people around him call him Mr. Trump. Seemingly aware that male candidates can get in trouble for how they refer to their opponents—pretty much the first thing any decent debate coach would have told him—he asked if she minded if he called her “Secretary Clinton,” perhaps hoping she would agree to first names, like when Sarah Palin asked Joe Biden for permission to call him Joe at the 2008 vice presidential debate. But Clinton didn’t budge, forcing Trump to stick to the imbalanced titles for the rest of the debate.

When moderator Lester Holt asked Donald Trump about his comments that Clinton did not have a “presidential look,” Trump tried to change the subject. “She doesn’t have the look. She don’t have the stamina,” he said. “And I don’t believe she does have the stamina to be president of this country, you need tremendous stamina.”

Clinton had a quick retort: “As soon as he travels to 112 countries and negotiates a peace deal, a cease-fire release of dissidents and opening of new opportunities and nations around the world or even spends 11 hours testifying in front of a congressional committee, he can talk to me about stamina,” she said.

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Still the battle was not quite as bloody as some expected. Trump refrained from some of the more egregious behavior that he had used in primary debates. Perhaps taking a lesson from his high-profile spats with Megyn Kelly and Carly Fiorina, he did not make any comments about Clinton’s appearance. He did not call her any names to her face, the way he did with Marco Rubio and Ted Cruz during the primary debates. And after hinting that he would invite Bill Clinton’s ex-lover Gennifer Flowers to the debate, the campaign backed away from that idea over the weekend.

Clinton, meantime, pressed her advantage. In order to highlight his record of offensive comments towards women, she brought up a former Miss Universe winner, Alicia Machado, who recalls Trump called her “Miss Piggy” and “Miss Housekeeping.” Shortly after the debate concluded, the Clinton campaign released a video featuring Machado speaking in Spanish about how Trump had shamed her for gaining weight, withheld her pay and caused her to develop an eating disorder.

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Trump’s oddest moment came when he brought up a longtime feud with actress and daytime talk show personality Rosie O’Donnell, whom he’s called a “slob” with a “fat, ugly face.” After Clinton brought up Machado, Trump inexplicably brought up his long history with O’Donnell as a retort. “You know, Hillary is hitting me with tremendous commercials. Some of it’s said in entertainment. Some of it’s said — somebody who’s been very vicious to me, Rosie O’Donnell,” he said. “I said very tough things to her, and I think everybody would agree that she deserves it and nobody feels sorry for her.”

After the debate, Trump suggested that he had been holding back his worst criticism of Clinton, and that the gloves might come off in a future debate. He hinted that he might bring up her husband’s sexual infidelity. “I’m very happy that I was able to hold back on the indiscretions with respect to Bill Clinton because I have a lot of respect for Chelsea Clinton,” he told CNN after the debate. “And I just didn’t want to say what I was going to say.”

What was that exactly?

“I’ll tell you maybe at the next debate.”

Clinton came out on top in this battle, but for the next six weeks, this is war.