The warm-up rounds are over. For the first time, all the top Democratic presidential candidates were on the debate stage together and the results were crackling.
No more theoretical discussions of how candidate x on day one looked compared to candidate y on day two. No more sparring with lower-tier candidates who served as surrogates for stronger candidates not in the room.
No more Queensberry rules of boxing. It was a bare knuckle affair.
Here are some of the biggest moments so far.
The first question, as it was during the earlier debates, was healthcare – an issue polls regularly show ranks high for American voters.
The fault line within the Democratic Party currently sits between candidates who want to do away with private insurance in place of a nationalised health system and those who want a “public option” that competes with private insurers.
Democratic frontrunners spar over healthcare
That source of friction was on full display Thursday night. Joe Biden, sandwiched between the progressive duo of Elizabeth Warren and Bernie Sanders, sparred with them both.
Regarding Sanders’s assertion that businesses will give savings back to workers from not having to pay their insurance, the former vice-president quipped: “For a socialist you’ve got a lot more confidence in corporate America than I do.”
He wondered aloud how any of the progressive candidates would pay for their sweeping plans.
Between Sanders and Warren, the latter offered the most skilful response. Sidestepping questions about whether her plan would raise middle-class taxes, she said the issue was the costs of the current system – in insurance premiums, out-of-pocket deductibles and medical care forgone because of the expense.
“What this is about is making sure we have the most efficient way possible to pay for healthcare in this country,” she said.
The real fireworks erupted later, when the lower-tier candidates chipped in. Amy Klobuchar said Sanders’ plan was a “bad idea”. Pete Buttigieg said it “doesn’t trust the American people” to choose between public or private options.
Then Julian Castro lashed out at Biden, in perhaps the most jarring exchange of the night. The topic, whether poor Americans are automatically covered by government insurance, was beside the point.
The critical moment came when Biden disagreed with Castro’s assertion, and the former Obama cabinet secretary accused the former Obama vice-president of “forgetting already what you said just two minutes ago”. For the first time a candidate all-but-directly questioned the 76-year-old Biden’s mental faculties.
Whether or not that jab leaves a permanent mark – and whether, if it does, it helps Castro – the glass has been broken.