If there was ever any doubt about whether a debate could change the course of a presidential campaign, it's recently been put to rest.
So both Donald Trump and Kamala Harris are awake to the high stakes as they prepare to face off.
The debate is being hosted by America's ABC network in Philadelphia, Pennsylvania – one of the crucial battleground states that both candidates have been targeting during the campaign.
Given how close the polls are, including in those swing states, this debate has the potential to have a big impact on the race for the White House, again.
What time is the presidential debate?
It's today at 11am AEST in Australia.
The debate is happening in Philadelphia and is scheduled for 9pm on Tuesday, September 10, local time.
How can I watch the debate in Australia?
In Australia, you can watch on the (Australian) ABC News Channel, including on YouTube and iview.
We'll also be live blogging the debate here on the ABC News website with our experts in the US and Australia.
America's ABC will stream the debate on its website and YouTube channel.
What are the rules this time?
They're very similar to last time:
The debate will go for 90 minutes, with two commercial breaks.
Candidates will have two minutes to answer each question, with a two-minute rebuttal, and an extra minute for a follow-up, clarification or response.
There will be no audience. (But, unlike the CNN debate, some reporters will be allowed in the room.)
No props are allowed.
No pre-written notes are allowed, but candidates will be given a pen and paper.
Microphones will be muted except for when candidates are asked to speak.
There will be no opening statements. The candidates will be asked to give two-minute closing statements.
ABC anchors Linsey Davis and David Muir will ask the questions.
Trump last week won a coin toss and opted to give his closing statement last.
Harris chose to stand at the podium on the right of screen.
Have Harris and Trump debated before?
No. In fact, Harris and Trump have not met in person. According to CNN, the only time they've been in the same room was during Trump's State of the Union addresses to Congress.
This is the second, and possibly final, presidential debate of the 2024 election campaign.
The first was hosted by CNN on June 27, local time. Of course, that debate was between Trump and President Joe Biden, whose poor performance triggered a crisis of confidence among Democrats that ultimately led to Biden's withdrawal from the election.
Here are the key takeaways from that event.
Harris's last election campaign debate was against Trump's then-vice-president, Mike Pence, during the 2020 race.
Their only debate was a less fiery affair than those involving the presidential contenders, Trump and Biden. But Harris – who was separated from her opponent by a plexiglass screen because of the pandemic – inspired some viral content by twice shutting Pence's interruptions down with the line, "I'm speaking."
There were few standout moments, though, as both vice-presidential candidates aimed to do what vice-presidents are supposed to do – avoid stealing the limelight.
It's telling that the big meme-generating moment came thanks to a housefly that perched itself on Pence's head and stayed there for a good couple of minutes.
Last week, Trump said Harris was a "nasty person" and "the way she treated Mike Pence was horrible". (Pence has refused to endorsed Trump, whose supporters brought a noose to the Capitol and chanted "hang Mike Pence" during the January 6 insurrection.)
Both candidates complain they're disadvantaged
True to form, Trump has been trashing the host network and attempting to set early expectations that the debate is stacked against him.
"ABC is the worst network in terms of fairness," he told Fox News last week.
"They are the most dishonest network, the meanest, the nastiest, but that was what I was presented with."
Trump has also complained that Harris's "best friend is the head of the network", an apparent reference to Dana Walden, the co-chair of Disney Entertainment, which owns America's ABC.
Walden and her husband are long-time friends of Harris and second gentleman Doug Emhoff. The couple has donated to Harris's past political campaigns, and they held a fundraiser for her at their LA home in 2022.
But Disney says Walden is only involved in corporate matters, like budgets and staff size. The company recently told the New York Times that "all editorial decisions are in the hands of ABC News management and the seasoned journalists and producers of ABC, who hold themselves to the highest journalistic standards".
The Harris campaign is also complaining of being disadvantaged, after it failed to persuade ABC to keep both candidates' microphones on throughout the debate.
"Vice President Harris, a former prosecutor, will be fundamentally disadvantaged by this format, which will serve to shield Donald Trump from direct exchanges with the Vice President," the Harris campaign wrote in a letter to ABC.
How have they been preparing?
Harris's debate preparation appears to have been more intense than Trump's.
She's been staying at a hotel in Pittsburgh, Pennsylvania, doing some practice sessions with trusted staff.
One of them is Philippe Reines, who has been playing the part of Trump in mock debates. He did the same thing for Hillary Clinton back in 2016.
Trump told a New Hampshire radio station that there was "not a lot you can do" to prepare, but that he had "been prepared for this debate my whole life".
"You can't sit in a log cabin like [2012 Republican presidential candidate] Mitt Romney," Trump said. "Do you remember? He sat there for four weeks at a log cabin, didn't talk to anybody, and then he came out, he couldn't speak. You can't do that."
However, the New York Times reported at the weekend that Trump was having multiple debate preparation sessions, and had put in more work to prepare for the 2024 debates than he did in 2016 or 2020.
When is the vice-presidential debate?
Harris's running mate Tim Walz and Trump's running mate JD Vance have agreed to debate on October 1.
That debate is set to be hosted by TV network CBS in New York City.
When is the US election?
It will take place on Tuesday, November 5, 2024.
Polls will open as early as 5am local time in some jurisdictions and close as late as 8pm.
