The pace was faster and the barbs sharper at the second Democratic primary debate.

But while several candidates landed blows on the frontrunner, former Vice President Joe Biden, only one slayed: Sen. Kamala Harris (D-CA).

It was plain from her first answer that Harris was playing to win, using a question about whether ambitious and expensive Democratic proposals should be paid for by hitting President Donald Trump’s signature tax-cut legislation. But it was an exchange with Biden that made it clear she had come to Miami to capture the crown.

The moment came after the conversation had turned to race, with the moderators asking South Bend Mayor Pete Buttigieg about the tensions in his city following the shooting of a black man by a white police officer. As the rest of the field tried to jump in, and the moderators attempted to pose a question for Biden, it was Harris who cut in.

“As the only black person on this stage, I would like to speak on the issue of race,” the senator said, causing the moderators to yield and the rest of the stage to fall silent.

“So on the issue of race, I couldn’t agree more that this is an issue that is still not being talked about truthfully and honestly,” she began, recalling how as a child, a neighbor would not let her children play with her and her sister because of the color of their skin.

Then, she pivoted to Biden.

“I do not believe you are a racist,” she said, ominously, as Biden appeared to look down at his notes. “I agree with you when you commit yourself to the importance of finding common ground. But I also believe and it’s personal and it was hurtful to hear you talk about the reputations of two United States senators who built their reputations and careers on the segregation of race in this country.”

She wasn’t done.

“It was not only that, but you also worked with them to oppose busing and there was a little girl in California who was part of the second class to integrate her public schools and she was bussed to school every day,” she said. “That little girl was me.”

Biden turned to look at Harris, as she continued.

“So I will tell you that on this subject, it cannot be an intellectual debate among Democrats, we need to take it seriously, we have to act swiftly,” she added for good measure.

It may not have been a fatal blow. But it was a knockout.

“I think the moment will resonate with voters not only because of how powerful and deft Kamala Harris was, but equally also because how ill-equipped Biden was in his response,” said Patti Sollis Doyle, who served as Hillary Clinton’s campaign manager in 2008. “I think voters will say to themselves, if she can do that to Biden, imagine what she can do to Trump.”

Biden, for more than a week now, had been dogged by comments he had made at a private fundraiser in which he praised the political civility of two pro-segregationist senators he had worked with in the ’70s. Before then, his record on bussing had posed problems for his campaign.

It was in the mid-1970s that Biden argued against efforts to bus children to different neighborhoods in order to promote diversity. At the time, and in the years after, Biden has explained it was the government’s role in integration he opposed, not the practice of integration itself—a line of argument that continues to sit poorly with those who see the federal government as an integral force in bringing about an end to societal racism.

“It’s a mischaracterization of my position across the board,” Biden said Thursday night. “I do not praise racists. That is not true, No. 1. No. 2, if we want to have this litigated on who supports civil rights and whether I did or not, I’m happy to do that.”

“I was a public defender,” he said, before turning to Harris. “I was not a prosecutor,” he added, as a clear dig at Harris’ record as a law-enforcement official in California.

Rep. Cedric Richmond (D-LA), a Biden supporter, defended him to reporters after the debate, saying the former VP didn’t have adequate time to explain his reasoning.

“I think he started to go into it and didn’t explain his entire record on bussing,” he said. “His record on going in and righting injustices especially based on race is one that I can defend and I’m proud of.”

But, Richmond said, the attacks on Biden were expected.

“Look, he’s the frontrunner; everybody’s going to come after the frontrunner,” he said.

To be sure, Harris wasn’t the only one to take a shot at Biden. But even the moments when she wasn’t leading the charge, she still got the last word. At one point, Rep. Eric Swalwell (D-CA) told a story about how, as a 6-year-old, he saw Biden speak at the California Democratic Convention about the need “to pass the torch to a new generation of Americans” before imploring him to consider doing that now. Biden shot back, “I’m still holding on to that torch.”

The debate then broke down into a cacophony of crosstalk: Buttigieg said as the youngest person on the stage he should weigh in, Sen. Bernie Sanders (I-VT) yelled in his customary monotone about how Wall Street has no generation, and Sen. Kirsten Gillibrand (D-NY) tried to interject to get more than 10 seconds of air time.

Then Harris spoke, separating herself from the field for the first time of the evening.

“Hey, guys, you know what? America does not want to witness a food fight, they want to know how we are going to put food on their table,” she said.

The line got a massive applause from the crowd. But they weren’t the only ones to notice. Harris’ performance caught the attention of Trump world too, where aides who watched the debate play out brought her name up again and again. In fact, seven different Trump allies replied with her name when asked mid-debate who was dominating the stage.

“The only Democrat who hasn’t hurt themselves so far is Kamala Harris,” said a source close to the White House. “Her years as a prosecutor clearly prepped her for coming across strong in this type of environment.”

One Trump campaign adviser noted that Harris was highly effective in her prolonged exchange with and attack against Biden. Barry Bennett, a senior adviser on the 2016 Trump team, agreed that Harris was giving her fellow Democrats on the stage a run for their money, though he said, “It’s like being the tallest dwarf.”

One name that did not come up: Biden.

Throughout the debate, he appeared defensive and at times shaky, making statements about the importance of the future, only to keep getting dragged back to his record from the past. And even at his most combative—as he defended his record on race after Harris’ verbal pummeling—he seemed to run out of gas.

“Anyway, my time is up,” he concluded, voluntarily ceding his time to the waiting moderator.

—With additional reporting by Asawin Suebsaeng, Gideon Resnick and Sam Stein