LAS VEGAS — Mike Bloomberg became a piñata, and Elizabeth Warren resurrected her feisty side.

The Democratic candidates formed a circular firing squad Wednesday night, with arrows flying in all directions and fights breaking out among a seemingly infinite permutation of candidates on matters from health care policy to lewd comments about women.

The debate was not only Bloomberg's first time on a presidential debate stage; it was also the first night of his surging 2020 campaign that wasn't choreographed. The result: He faced direct criticism from rivals he has bested in recent polls. It was the most contentious evening of the nine faceoffs so far, coming three days before the candidates face the most diverse voting electorate yet in their quest to make Donald Trump a one-term president.

"It's a little bit like a presidential version of 'Survivor,'" former Sen. Claire McCaskill, D-Mo., said on MSNBC after the debate.

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Here's a look at who was the most aggressive, who took the toughest punches and who missed their marks over the course of the debate, which was hosted by NBC News, MSNBC, Telemundo and The Nevada Independent.

Mike Bloomberg

It was the billionaire entrepreneur's first time on the debate stage, and his rivals made the most of it. He was slammed on everything from his record on stop-and-frisk to the millions he's sinking into his campaign. Bloomberg kept his composure, standing stone-faced, barely smiling, but he seemed unprepared for an entirely predictable series of attacks.

He said he's "embarrassed" about the "stop and frisk" strategy police pursued when he was mayor of New York: "I've sat, I've apologized, I've asked for forgiveness." Pressed on why he hasn't released his tax returns, he said "it just takes a long time" because of his extensive business dealings and "I can't just go to TurboTax."

His low point came when he refused Warren's demands to release women he has worked with from nondisclosure agreements — and he was booed for saying "we're not going to end these agreements, because they were made consensually."

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Bloomberg pitched himself as a mayor, a manager and a philanthropist. He also took a shot at Sen. Bernie Sanders, I-Vt., the front-runner in recent national polls, calling him unelectable: "I don't think there's any chance of the senator beating Donald Trump." Later, he added, "The best-known socialist in the country happens to be a millionaire with three houses."

Bernie Sanders

Sanders entered the debate as the front-runner for the nomination — in Nevada and nationally — and nothing in the debate knocked him off his stride. Bloomberg counterpunched, Pete Buttigieg lobbed criticisms (and a bit of praise) and Joe Biden and Amy Klobuchar noted his vote against a 2007 immigration bill.

It gave Sanders the space to press his righteous indignation against an economically unequal society. He spent much of the debate ripping into Bloomberg, repeatedly calling him part of a ruling elite that has manipulated Washington to establish policies that benefit people like him personally. He alluded to a "corrupt political system bought by billionaires like Mr. Bloomberg" and said it's immoral that "Mike Bloomberg owns more wealth than the bottom 125 million Americans" when many of them are suffering.

Elizabeth Warren

Warren, a senator from Massachusetts, dispensed with the milquetoast unifier persona that served her poorly through Iowa and New Hampshire and revived the fiery progressive warrior more reflective of her authentic self. She lit into Bloomberg over past sexist remarks and nondisclosure agreements with women, declaring, "America takes a huge risk if we just substitute one arrogant billionaire for another."

She confronted Biden, Buttigieg and Klobuchar, as well: "Amy and Joe's hearts are in the right place, but we can't be so eager to be liked by Mitch McConnell that we forget how to beat the Republicans. Mayor Pete has been taking money from big donors and changing his positions. So it makes it unclear what he stands for."

Warren desperately needed a boost after poor finishes in early states, and she turned in one of her strongest and feistiest debate performances yet. She delivered aggressive pitches to close the racial income gap, enact her 2-cent wealth tax on assets above $50 million and deliver environmental justice. One sign she did well? Her campaign announced midway through the debate that it was her best hour of fundraising to date.

Joe Biden

The former vice president, bleeding support nationally after poor showings in Iowa and New Hampshire, sought to correct course with a performance that was at times lively.

He went after Bloomberg repeatedly, starting with his criticism of the Affordable Care Act after it was passed — "Mike called it a disgrace," Biden said. He jumped in at various times to remind voters that he's "the only one" who has actually dealt with foreign leaders and led the charge on major pieces of legislation. He faced a yelling protester at the end of the debate, and he used his closing statement to go after Sanders for voting against a 2007 bill that would have created a pathway to citizenship for people in the U.S. illegally.

It's not clear, however, that Biden did what he needed to do to alter the trajectory of his polling decline. He got the second-lowest talking time of the debate, after only Bloomberg.

Pete Buttigieg

Buttigieg, facing a new test in a more diverse state after strong showings in Iowa and New Hampshire, urged Americans not to let Sanders and Bloomberg become the only two choices, saying the senator wants to "burn this party down" and the billionaire wants to "buy this party out."

He criticized Sanders over the mammoth cost of his health care plan. But he also repeatedly went after Klobuchar, who's cutting into his support among moderates but is polling well behind him overall. He took her to task for failing to name the president of Mexico, and he knocked her for voting for many of Trump's judges and his head of Customs and Border Protection, Kevin McAleenan. Her pithy retort: "I wish everyone was as perfect as you, Pete."

In his closing statement, Buttigieg, the former mayor of South Bend, Indiana, pressed his message of uniting the U.S.: "We can't afford to alienate half the country. We must step forward into the future."

Amy Klobuchar

Klobuchar, a senator from Minnesota, impressed at the New Hampshire debate and finished a better-than-expected third in the primary. But Nevada is another matter — a test of her ability to appeal to a more diverse electorate.

Klobuchar pressed her message as a pragmatist and a doer, but it remains to be seen whether she did anything to boost her poor support among Latino and black voters.

Her fieriest moments came when counterpunching against Buttigieg's attacks. "You've not been in the arena doing that work. You've memorized a bunch of talking points and a bunch of things," she told him.