Vice President Joe Biden and Republican Paul Ryan, the man who wants his job, exchanged fire over taxes, Medicare, national security and some animated facial expressions in their only debate before Election Day.
Here are five things we learned from Thursday night:
1. Biden brought it
We expected Ryan, not Biden to bring a three-ring binder full of facts and figures to the debate. It's not that the data-driven Ryan didn't show up with an arm full of his statistics; it is just that Biden did so as well.
And Biden's aggressive offense from the very beginning drowned out Ryan until about 45 minutes into the debate.
Biden's 36 years in the Senate served him well Thursday night. Who says that delivering hundreds of floor speeches on Capitol Hill isn't useful? The vice president also proved wrong the critics, who predicted he was going to make a gaffe. He didn't.
In many ways, Biden stole a page from Mitt Romney's debate playbook: put your head down, charge forward and don't stop. Romney effectively employed this strategy last week and Barack Obama was never able to recover. While Ryan put up a fight last night, he, too, was unable to regain his footing.
An Obama-Biden campaign official said before the debate that the vice president's goal was to try and compare and contrast the two competing campaign's vision for the future. Whether you agree or disagree with the specifics of the Obama-Biden or Romney-Ryan plans, Biden did a better job of selling his last night.
It will be several days until we know if this debate has helped the Obama-Biden campaign stem the political bleeding. But Biden did what he needed to do.
2. Too much Joe?
If Biden was on a mission to bring the fight to Ryan, then it appeared to be mission accomplished for the vice president.
Moments into the debate, Biden went on the attack.
"On Iraq, the president said he would end the war. Gov. Romney said that was a tragic mistake," said Biden.
Minutes later the vice president pushed back against criticism by the Wisconsin congressman, saying "not a single thing he said is accurate."
And he called other accusations by Ryan "a bunch of stuff."
Biden went where President Barack Obama wouldn't last week in his debate with Romney, bringing up Romney's "47%" controversy as well as the Republican nominee's tax rate.
And later, when Ryan discussed President John F. Kennedy's tax policies, Biden fired back: "Oh, now you're Jack Kennedy?"
"The vice president came and showed fight. He showed his boss what it is to engage and engage and engage and attack and attack and attack," said CNN Chief National Correspondent John King.
"I think Joe Biden did do his boss a lot of help," agreed Senior CNN Political Analyst David Gergen, who's advised both Democratic and Republican presidents.
But was Biden too aggressive?
"I think Joe Biden is an authentic person. He speaks his mind. People know him. They expect that," Obama senior adviser David Axelrod said. "I think that authenticity is something that people appreciate."
The Romney campaign disagreed.
"The sighing, the eye-rolling, the grinning. I don't know if the vice president knew that there was a camera on him the whole time, that there was a split screen," senior Romney campaign adviser Russ Schriefer said. "Even if we thought he was making good points, I think that they stepped on his good points. He was trying to cram everything in that he could that wasn't in the last debate to try and get it all out at once. But I don't think he made any kind of coherent argument as to why the Obama-Biden ticket should be re-elected."
Gergen agreed: "On style I think that Paul Ryan won the debate. The Biden dismissive laughs, the interruptions, the sort of shouting, I think that Ryan was calmer and frankly more presidential."
What did debate watchers think? Seven out of 10 debate watchers in a CNN/ORC International poll said that Biden was the aggressor.
3. Does the debate even matter?
The short answer is no.
People don't vote for vice presidents at the ballot box. They vote for presidents. Past vice presidential debates, no matter how high the drama, have ultimately done little to move the needle in modern elections.
Not surprisingly, Biden's scenery-chewing performance was viewed differently by both campaigns. The Romney campaign said he looked erratic, rude and unhinged. The Obama campaign said he laid out the facts and made Ryan look, in the spin room words of former Ohio Gov. Ted Strickland, "like a lightweight."
But a common refrain from both campaigns after the debate was that it will probably have a minimal effect on the race one way or the other.
The biggest impact of the night, and the reason Democrats were ebullient after the debate, was the base-rallying impact of Biden's aggressive and blustery stage presence.
In the wake of Obama's wilting flower routine in last week's debate, the full Biden, exasperated and angry with Romney and Ryan, was just what Democrats needed.
How happy was team Obama? Campaign surrogates stayed in the spin room with puffed chests for much longer than they did in Denver, when they offered dubious messaging before escaping. The campaign immediately sent out a fundraising plea. President Obama put himself in front of cameras after landing at Andrews Air Force Base to praise Biden's performance.
And it wasn't just the Obama camp.
Democratic state parties, liberal interest groups and down-ballot campaigns rushed to send out fundraising e-mails to capitalize on a fired-up base. You didn't see much of the same on the Republican side.
The debate launched a fresh news cycle that will put a temporary halt to the "Chicago in disarray" storylines. Now the pressure is on President Obama to keep that narrative going next week in New York.
4. Ryan rises to challenge
It was arguably Ryan's biggest task in the vice presidential debate.
As the running mate to the Republican challenger, Ryan needed to convey that he's fit to serve should something happen to the commander in chief, that he would be acceptable to Americans as president.
Known as an expert on economic and budget issues, early in the debate Ryan showed his smarts on foreign policy. During a discussion on troop drawdowns in Afghanistan, he explained how the seasonal changes affect the fighting in Afghanistan.
"The mountain passes fill in with snow. The Taliban and the terrorists and the Haqqani and the Quetta Shura come over from Pakistan to fight our men and women. When it fills in with snow, they can't do it. That's what we call fighting seasons. In the warm months, fighting gets really high. In the winter, it goes down," explained Ryan.
"And so when Adm. Mullen and Gen. Petraeus came to Congress and said, if you pull these people out before the fighting season ends, it puts people more at risk. That's the problem."
"I think Ryan proved himself unexpectedly competent on foreign policy," said Republican strategist and CNN contributor Alex Castellanos, who worked for Romney's 2008 presidential bid. "I think Ryan met his test tonight. Ryan looked very reasonable."
As expected, the Obama campaign disagreed.
"I think Congressman Ryan was out of his depth and showed clearly the ticket is not ready for prime time on foreign policy, and I think that was a decisive difference between the two sides," said Obama campaign manager Jim Messina.
So what do debate watchers think? Did Ryan pass the competency test?
Six out of 10 debate watchers in the CNN/ORC poll conducted said that Ryan is qualified to be president.
5. Malarkey moves numbers
"Malarkey" is one of Biden's favorite Biden-isms.
He's been saying it for decades, but not usually with the kind of gusto he showed on Thursday before millions of prime time television viewers.
Soon after the debate began, when Ryan criticized the Obama administration's foreign policy, Biden fired back: "With all due respect, that's a bunch of malarkey."
What does malarkey mean?
People apparently rushed to their computers to find out. "Malarkey," it turns out, was the third-most-searched debate-related term of the night on Google. It was also trending on Twitter for a good chunk of time.
For the record: it's basically the Irish-American term for "nonsense."
According to Google, the other top searches during the debate were "Biden," "conflating," "Who is winning the debate" and "How old is Paul Ryan."