After months of tangling from afar, Democratic Hillary Rodham Clinton and Republican Donald John Trump will confront each other face-to-face for the first time in Monday night's presidential debate, laying out for voters their vastly different visions for America's future.
Stakes are high for the first nationally televised showdown between the two contenders of White House race, with latest polls showing the Democrat and former secretary of state's once sizeable lead vanishing against the controversial non-politician.
A record 100 million Americans are expected to tune in for 90 minutes to watch the first presidential debate, six weeks before the polls this year that could see a lot of drama and putdowns in the wake of similar trail during the Republican primary debates by the 70-year-old reality TV star.
The figure, if turns out to be true, would surpass the record of 80 million who watched the 1980 encounter between Democratic President Jimmy Carter and Republican Ronald Reagan.
Locked in a neck-and-neck battle with just over a month to go for the elections, the two leaders will take centrestage at Hofstra University in Hampstead, about an hour's drive from New York City, for the first of a series of three presidential debates.
The debate is the biggest matchup since last year's historic Floyd Mayweather Jr- Manny Pacquiao fight, according to David Kostin, the chief US equity strategist at Goldman Sachs.
Kostin said that it is expected to be the most watched presidential debate ever and characterized it as nearly approaching "Super Bowl proportions with an audience of perhaps 100 million."
Clinton, 68, who is the first-ever woman to be nominated as a presidential candidate by a major political party, and the real estate mogul are in virtual dead heat, with a latest poll showing a bare two-point lead for the former secretary of state.
"I think this thing will be close right up until the end," said Clinton running mate Tim Kaine. "We have to make our case every day. The debates are a great way to do that."
Analysts say a lot would be at stake for the two leaders as a single sentence or the slightest slip can do serious damage at this crucial time.
Trump - who nobody took seriously when he filed his nomination papers last year for the first time - has risen despite infighting to be the party's top candidate for the race to the White House but has faced flak for what many believe is a "hateful" rhetoric - against women, non- Americans, Muslims and so on.
Clinton, on the other hand, has been embroiled in questions about her family foundation and her use of a private email server while she was the secretary of state under incumbent President Barack Obama.
The controversies seem to have cost Clinton, who is eyeing to break the highest glass ceiling in the US and has constantly led in polls since this summer, the popularity as reflected in latest polls that have cut down her lead over Trump significantly.
The two candidates, who polls have also shown to be the least liked White House candidates in modern history, hope to use the debate to instil more confidence among voters.
The debate will also show if Clinton's latest bout of illness, due to which she took a couple of days off from campaigning, has had any impact on the voters, even as Trump continued with campaigning till the last minute and had said he was "ready" for it.
Clinton's camp is worried that Trump will be held to a different standard in the debate and is particularly concerned that the notoriously hot-headed businessman will be rewarded for simply keeping his cool.
"We also are concerned that Trump is going to continue to lie," Clinton's campaign manager, Robby Mook, said Monday.
The debate about the debate was still unfolding in the hours before the two candidates were to take the stage.
Clinton backers were publicly pressing moderator Lester Holt of NBC News to fact-check Trump if he tries to mislead voters about his record and past statements. But Trump's campaign pushed back, accusing Clinton's team of trying to put its thumb on the scale by enlisting the media to do Clinton's job for her.
Asked about Trump's incorrect statement that Holt is a Democrat — he's registered as a Republican in New York — Trump campaign manager Kellyanne Conway said it wasn't lie, because Trump simply didn't know Holt's voter registration.
"He didn't lie. A lie would mean he knew the man's party affiliation," Conway said on MNSBC.