The third presidential debate was to focus on debt and entitlements, immigration, the economy, the Supreme Court, foreign hotspots and fitness to be president — serious and somber topics.
But that did not factor in the unpredictability of this long and often nasty campaign. In the week and a half since the second debate, Donald Trump was accused of sexual misconduct by nine women, allegations he denies; repeatedly warned of a rigged election without evidence and turned his ire on his party's most senior official, House Speaker Paul Ryan.
Hillary Clinton, meanwhile, faced questions raised by leaked information supposedly from John Podesta’s emails — made public by WikiLeaks and allegedly stolen by Russian hackers from the Clinton campaign chairman's personal account.
Here are some of the top moments from the final debate before Election Day.
Accepting the Results?
Trump, who has warned of a rigged election that will deny him a victory, refused to say whether he would accept the results of the presidential election.
"I will look at it at the time," he told debate moderator Chris Wallace, provoking a gasp from some in the audience.
Explaining his stance, he repeated a frequent accusation that the media was corrupt.
"I will tell you at the time," he said. "I'll keep you in suspense."
Clinton called the statement "horrifiying."
'Such a Nasty Woman'
As Clinton discussed how she would continue to finance Medicare and Social Security, she said she would not cut benefits but would raise taxes on the wealthy. Her Social Security payroll contribution would rise, she said.
"As will Donald’s, assuming he can't figure out how to get out of it," she said, in a dig at Trump, who reportedly used a $916 million loss to avoid paying personal federal income tax for years.
"Such a nasty woman," Trump retorted.
Earlier in the debate, Trump said, "no one respects women more than I do," a claim he often makes.
Sexual Misconduct Returns
Trump denied at the debate that he engaged in any sexual misconduct, after nine women have accused him of doing so in the last 10 days.
"I didn't even apologize to my wife who is sitting right here because I didn't do anything," he said.
He said he believed that Clinton's campaign had gotten the women to step forward together at a politically opportune time.
Clinton said his response to the allegations was to mock the appearance of his accusers, saying they were not attractive enough or not his first choice.
"Donald thinks belittling women makes him bigger," she said.
Trump pivoted to a charge that Clinton had illegally destroyed emails on her private server.
Clinton, for her part, avoided a question about whether what her husband had done was worse.
'We Need a Wall'
Trump promoted one of his biggest selling points: building a wall on the U.S.-Mexico border, which he has said Mexico would pay for. Drugs are flowing across the border, he argued, and he said he would stop it by sending drug dealers back.
"We have some bad hombres here," Trump said.
Clinton responded that when Trump met with the Mexican president, Enrique Pena Nieto, he failed to raise the issue at all.
"He choked," she said.
Wallace asked Clinton about a speech that she had made to a Brazilian bank in which she dreamed of open borders — to which Clinton responded that she was talking about energy and an electric grid.
In a tit for tat, Trump taunted Clinton with wanting a wall but failing to get one built because, he said, she never got anything done.
Clinton argued that she voted for a border security plan that called for wall in some places and then accused Trump of using undocumented labor to build Trump Tower. Anyone who complained was threatened with deportation, she said.
Who's Putin's Puppet?
When the hacking of Clinton's emails came up at the debate, the conversation quickly pivoted to the leader of Russia, and Trump and Clinton debated who Vladimir Putin really wants as president.
Trump repeated a frequent refrain from his stump speeches: "Wouldn't it be nice if we got along with Russia?" Then he said that Putin "has no respect for [Clinton], he has no respect for our president."
Clinton countered that Russia and the U.S. would get along with Trump as president "because he'd rather have a puppet as president."
"You're the puppet," Trump parried.
The candidates talked over one another, before Wallace interjected to ask if Trump would condemn Russia if they did hack a Clinton campaign email, as the Obama administration has said.
"Of course I condemn. I don't know Putin," Trump replied, then continued, "Putin has outsmarted her or Obama at every single step of the way."
The debate began on a less than cordial note. As they did at the second debate, the candidates stepped behind their lecterns without a handshake.
It ended the same way. Clinton stepped forward to shake Wallace's hand, then straight into the crowd. Meanwhile, Trump waited behind his lectern.
New Contentious Guests
Trump again invited some uncomfortable guests for the Clinton side, among them Leslie Millwee, a former Arkansas television reporter who has come forward to accuse Bill Clinton of sexually assaulting her while he was the state’s governor in 1980. An interview with Millwee was published on the right-wing website Breitbart on Wednesday. At Sunday's debate, Trump showcased three other women who have accused Clinton of sexual misconduct: Paula Jones, Kathleen Willey and Juanita Broaddrick.
Other guests invited by Trump to attend the Wednesday debate in Las Vegas: former vice-presidential candidate Sarah Palin and Patricia Smith, the mother of an American killed in Benghazi, Libya, during the 2012 attacks on a U.S. diplomatic compound. Smith, who spoke at the Republican National Convention in Cleveland, has said she holds Clinton accountable for "murdering" her son Sean.
The potential embarrassment for the Clintons reportedly prompted organizers to change the way the families would enter the debate hall so as to avoid any awkward handshakes.