WASHINGTON (AP) — What people remember from Joe Biden and Donald Trump's first debate four years ago are likely the interruptions, the shouting and the "will you shut up, man?"

Then-President Trump arrived at that first matchup in Cleveland seemingly determined to steamroll Biden at every turn, leaving the Democratic candidate exasperated and moderator Chris Wallace scrambling to regain control.

Now, in 2024, many of the rules insisted on this time by Biden's team — and agreed to by the Trump campaign — are designed to minimize the potential of a chaotic rerun. Each candidate's microphone will be muted, except when it's his turn to speak. There will be no studio audience to chime in with hoots and jeers.

The second and final presidential debate of 2020, held in Nashville, Tennessee, was a far more subdued event than the first, aided by a mute button and participants who were perhaps chastened by terrible reviews from the first matchup, particularly for Trump.

But if the Biden-Trump debate this Thursday in Atlanta spirals into pandemonium, consider that past was prologue.

A look back at that first Biden-Trump faceoff on Sept. 29, 2020:

The debate begins to devolveIt started out calmly enough, with a brief exchange about the Supreme Court vacancy that had opened up days before with the sudden death of Justice Ruth Bader Ginsburg. But the conversation turned contentious as the men tangled over health care and Trump's handling of COVID-19.

The sparring over the pandemic was tense enough — with Biden telling Wallace at one point, "You're not going to be able to shut him up." Then Biden pivoted back to the court and abortion rights, triggering yet another outburst from Trump that continued to irritate the Democrat (and likely Wallace, and perhaps the viewing public).

"The point is that the president also is opposed to Roe v. Wade," Biden said of Trump. "That's on the ballot as well and the court, in the court, and so that's also at stake right now. And so the election is all —"

"You don't know what's on the ballot. Why is it on the ballot?" Trump interrupted. "Why is it on the ballot? It's not on the ballot."

Trump would continue to interject until Biden showed his first real sign of irritation with his opponent and said: "Donald, would you just be quiet for a minute?"

But Trump didn't relent, refusing to let Wallace question him about his Obamacare replacement plan without interruptions and taunting Biden that his primary election victory over Vermont Sen. Bernie Sanders was "not by much" and that he "just lost the left" when he distanced himself from Sanders' vision for health care.

"Folks," Biden finally said, conveying his irritation to the audience, "do you have any idea what this clown's doing?"

Biden: "Will you shut up, man?"One clip replayed at length from the chaos in Cleveland was Biden finally snapping at Trump: "Will you shut up, man?"

It came during a discussion over progressive proposals to overhaul Senate procedural rules or the Supreme Court itself — topics that have been tricky for an institutionalist such as Biden. The Democrat was, as he openly admitted, refusing to answer the question.

So Trump took matters into his own hands.

"Are you going to pack the court? Are you going to pack the court?" Trump demanded as Biden tried to make a case directly to the audience. Trump muttered that Biden didn't want to answer the question.

"Why wouldn't you answer that question? You want to put a lot of new Supreme Court justices. Radical left," Trump concluded.

That's when Biden — again — lost patience. "Will you shut up, man?"

But Trump — again — wouldn't relent, forcing Wallace to cut the segment short and move on to a different topic. Biden lamented how unproductive the discussion was.

Trump insults Biden's intelligenceThe Republican also didn't hesitate to get personal, from attacking Biden's sole living son, Hunter, to mocking the Democrat's academic credentials.

It seemed like Trump had been waiting for Biden to use any derivation of the word "smart" to go after his intelligence. So when Biden warned that more Americans would die from COVID-19 unless the president got smarter in his handling of the pandemic, Trump pounced.

"Did you use the word smart?" Trump said. "So you said you went to Delaware State, but you forgot the name of your college. You didn't go to Delaware State. You graduated either the lowest or almost the lowest in your class."

"Don't ever use the word smart with me," continued Trump, who graduated from the University of Pennsylvania. "Don't ever use that word … Because you know what? There's nothing smart about you, Joe."

Biden received his undergraduate degree from the University of Delaware in Newark in 1965 and enrolled shortly thereafter at Syracuse University law school. He wasn't known for his stellar grades; at Syracuse, he graduated 76th in a class of 85.

Trump nods to the Proud BoysIt was one of Trump's most memorable moments that didn't involve interrupting Biden.

Wallace pushed Trump to condemn white supremacists and militia groups, particularly as the Republican president spent so much of his energy denouncing so-called "Antifa" or far-left militant groups.

Trump responded that he was willing to do so, but never explicitly condemned right-wing extremist groups by name. When goaded by Biden to condemn the Proud Boys, one of such groups on the right, Trump seemingly did the opposite.

"Proud Boys, stand back and stand by," Trump said. Those words, and the broader exchange, left some members of the neofascist group celebrating what they saw as an implicit approval from the president.

Trump was forced into clean-up duty one day later, saying he did not know who the Proud Boys were and adding that "whoever they are, they have to stand down. Let law enforcement do their work."

The contentious exchange about Biden's sonsBiden has long criticized Trump's attitude toward American troops, including his reported comments that in 2018, he did not want to visit a U.S. military cemetery in France because he thought the deceased soldiers were "suckers" and "losers."

"The way you talk about the military, the way you talk about them being losers and being, and, and, and just being suckers," Biden said to Trump. Speaking of his older son, Beau, a veteran who died of brain cancer, Biden continued: "My son was in Iraq. He spent a year there. He got — he got the Bronze Star. He got the Conspicuous Service Medal. He was not a loser. He was a patriot."

Trump swung back hard, taking aim at Biden's younger son, Hunter, instead.

"Are you talking Hunter? Are you talking about Hunter?" Trump responded, continuing: "I don't know Beau. I know Hunter. Hunter got thrown out of the military."

Trump then claimed that Hunter Biden was dishonorably discharged, which Biden quickly refuted. Hunter Biden was administratively discharged — which is not a dishonorable discharge — from the Navy in 2014 after testing positive for cocaine.

"My son … like a lot of people we know at home had a drug problem. He's overtaken it," Biden said, adding: "I'm proud of my son."

Biden commits to not declaring victory until the election is certified, Trump does notDuring the final moments of the first debate, Wallace asked both candidates whether they would commit to not declaring victory until the election had been independently certified, as well as urging their respective supporters to stay calm.

Trump declined to do so, instead saying he would encourage his supporters to go watch the polls and musing about election fraud.

Biden, in sharp contrast, responded to the same question: "Yes."

Trump, who would go on to lose the 2020 race, never conceded the election. Just over three months after the Cleveland debate, a mob of his supporters fueled by his election lies stormed the Capitol on Jan. 6, 2021.