Sin City is no stranger to prize fights and this one was a classic.
Both red and blue corners came out swinging, both Donald Trump and Hillary Clinton aware that this was the last chance they would have to speak directly to vast swathes of undecided voters tuning in around the country.
There was far more substantive policy discussion than in their previous encounters but there was still a good measure of rough and tumble, and bucket loads of name-calling.
The tone of this election cycle has been lowered so significantly that the shock standard is much higher.
Mr Trump repeatedly called Mrs Clinton a liar, a criminal and at one point interjected with a snide comment that she was "such a nasty woman".
Mrs Clinton for her part referred to Mr Trump as the "puppet" of Russian President Vladimir Putin, an exchange that descended into both shouting over each other and Mr Trump retorting with "no, you're the puppet".
That was one of the most bizarre but spiky exchanges of the night. Donald Trump quite remarkably saying "our country knows nothing" when it comes to what President Putin is doing, rejecting the proposition from Mrs Clinton that 17 civilian and military intelligence agencies were convinced that the "highest levels of the Kremlin" were behind the recent hacking of the Democratic National Committee and of the Clinton campaign chief John Podesta, incidents viewed as interference in the US election.
Mr Trump's temperament has been much discussed during this campaign, his quest as he puts it "to look presidential". He began the night very much in that vein. His voice was slower and lower than usual. He spoke in a controlled and deliberate manner and was convincing in his policies.
However, Mrs Clinton yet again engaged her strategy of gentle but repeated prodding, until the billionaire businessman eventually lost his cool. His voice rising in pitch and volume. His interruptions more frequent, even taking on the moderator Fox News host Chris Wallace.
Mr Trump also came across as a little bit slippery - any time he got a question he didn't like, he would dismiss the answer and quickly change the subject, which seemed skillful at first, but as the debate progressed, he repeated that "bob and weave" a few too many times, diverting into rambling answers that didn't really have any point to them at times.
He did manage to bring up a lot of the allegations about how the Clinton campaign is being run, claims that people were paid to disrupt Trump rallies. He also attacked the Clinton Foundation for how it fundraises and spends its money. But Mrs Clinton responded to that with questions about the Trump Foundation, neutralising his attack.
But the most controversial statement of all - and there were many - was his statement that he would not pledge to accept the election outcome if Hillary Clinton wins. This is an extension of his repeated catch all that this US political system is rigged. But this is really a pre-emptive strike, and advance rationale in case the man who prides himself on being a "winner", becomes a "loser", on a grand scale, or in his own words "big league".
He said that he will look at the election result "at the time" and decide whether to accept it, that he was "not saying anything now" and would keep voters "in suspense".
There is a great bipartisan tradition in America of a "peaceful transition" and the beaten candidate cordially supports the victor.
Many of Donald Trump's supporters and campaigners were quick to temper his remarks in the spin room after the debate, saying he had been misunderstood and he wasn't threatening the stability of the nation.
They drew parallels with Al Gore who did not accept the 2000 election result, vigorously challenged it, but ultimately conceded in the interests of the nation.
Mr Trump will do the same thing, if Hillary Clinton wins. But of course, from inside the Trump Train that is not a foregone conclusion.
In terms of the actual policy that was discussed last night, Mr Trump was far more low-key in his approach to immigration, there was no vitriolic pledge to "build a wall and make Mexico pay for it", but that was replaced with "We have some bad hombres here and we're going to get them out".
Perhaps most controversial was the discussion on abortion - the first time the candidates have properly engaged on this.
In every US presidential election, the candidates' position on abortion is a defining one for voters.
This was the first time they discussed the landmark case Roe v Wade - a Supreme Court ruling legalising abortion more than 40 years ago, and fought against by the Republicans ever since.
Mrs Clinton was very clear that she wanted it upheld, whereas although he was pressed upon it repeatedly by the moderator, Mr Trump could not bring himself to say that he wanted it overturned, other than to say it was the likely outcome once he had nominated a new Supreme Court justice. That will be something that will rancour with Republicans.
There was also quite a graphic discussion of late term abortions, with coarse language more usually seen at protest marches than on a presidential stage.
Unsurprisingly the question of women, and the number of women who have accused him of sexual assault in the last week, came up as part of a two-part question - about the women who have accused Donald Trump of sexual assault, and the women who have accused Bill Clinton of sexual assault, and Hillary Clinton of representing a rapist in court.
Interestingly, both candidates answered on the first part of the question and did not pick up on the Clinton accuser element.
But Donald Trump doubled down on his dismissal of the accusations against him, saying they have largely been "debunked" (they haven't), and claiming the women were either looking for fame, or had been put up to it be Hillary Clinton.
This section of the debate allowed Mrs Clinton to issue a call to arms to women across the country, to stand up for themselves, describing Mr Trump's negatives attitudes as ones most women had experienced at some point in their lives.
This was one of her strongest elements, the other being when she had a prepared answer, delivered well, to Donald Trump's attack on her for having been in public life for 30 years but not doing anything about America's problems.
She pitted her professional and political achievements and his, comparing her legal career to him getting a loan from his father, adding that while she was busy "taking out Osama bin Laden" he was hosting Celebrity Apprentice.
So just what impact will the debate have?
If you were an undecided voter, you would possibly be swinging more to Hillary Clinton's camp after this performance, purely because she retained her composure throughout, whereas Donald Trump became more and more rambling, and interrupted more and more as the debate proceeded.
He seemed at times like a man who could see the writing on the wall and was throwing everything at the wall as a result.
Both candidates are now straight back onto the campaign trail. Both are due to speak at a New York charity dinner tonight. Then they will focus on the swing states over the next few days that are really in play - Ohio, Florida, North Carolina and here in Nevada.
Mrs Clinton is dispatching her secret weapon, Michelle Obama, to Arizona today - an interesting indicator that the campaign is playing to win big, and not just edge over the finishing line.
Arizona is a Republican-stronghold where polls are showing Mrs Clinton stands a chance of victory - it's a similar case in Utah.
For the sake of uniting the country if she is elected, the bigger the margin of a victory the better.