Hillary Clinton and Donald Trump were dead even in the polls entering the first presidential debate. Now, as the candidates prepare to face off in their final debate on Wednesday night in Las Vegas, Clinton has a solid lead in national polls and several battleground states. For Trump, the debate in Las Vegas is his last big chance to win over voters before Election Day in November.

But it might be too late. The last debate comes at a point in the race when voters’ opinions of the two candidates have already hardened. And early voting is underway in many states. For millions of Americans, the election is already over, and the showdown in Las Vegas is far less important than the first debate last month. Still, it’s possible that Trump could pull off an upset. With that in mind, here is our viewer guide to the Clinton-Trump rubber match:

Emails, again

Way back when in their first primary debate, Bernie Sanders memorably told Clinton that Americans were “sick and tired of hearing about your damn emails.” But one year later, Clinton’s private email server scandal hasn’t disappeared. It’s been a prominent storyline throughout the campaign — and something Clinton will have to contend with for years to come, even if she wins the White House.

On Wednesday night, Clinton will face more questions about her emails, both from Trump and the moderator, Fox News anchor Chris Wallace. At the first two debates, Clinton tried to address the email question quickly and then pivot to an attack on Trump. The strategy largely worked at the first debate, and fell flat at the second.

The showdown in Las Vegas offers Clinton her last opportunity before Election Day to address the issue in front of tens of millions of voters. So will she try out a new, less defensive posture, or stick with her less-is-more approach? If Clinton takes the latter path, it will signal an 11th-hour effort to connect with voters who see her as untrustworthy. But it’s highly unlikely Clinton will change course and open up more this late in the race. Her team seems intent on minimizing the issue as much as possible. Don’t expect anything different in Las Vegas.

Experience counts. Or does it hurt?

At the second debate, Clinton had an effective response ready when Trump criticized her for failing to fix the nation’s problems over her 30-plus years in public service. Clinton has added a longer version of the answer to her stump speeches since the debate. If Trump wants to attack her record as a First Lady, senator and secretary of state, Clinton said at one recent campaign stop, “Bring it on.”

It’s a good line. But it cuts both ways. On the one hand, Clinton can point to a long track record of working on health care, women’s rights and other issues. Highlighting that at the third debate would no doubt rally her base. And it could also motivate undecided voters who remain worried about Trump’s lack of experience.

But whenever Clinton defends her past, it’s a reminder of her insider Washington status. That’s dangerous in a year in which many voters want to shake things up. Trump’s 30-year line of attack at the second debate struck a chord, even though Clinton had a ready answer. On Wednesday, Clinton will likely have to thread that needle again, and it won’t be easy.

This could get serious

We know that many of you may be thinking some version of “the last three debates — including the vice-presidential debate — have been more food fight than illumination.” We agree. But we offer two reasons to hope for a more serious discussion. First, the moderator. FOX News’ Chris Wallace has shown on his Sunday morning show and, more to the point, in 2016 primary debates, that he will ask tough, serious questions and not allow candidates much room to launch the debate off the rails. In a race where the Republican nominee routinely points to media advantage, this debate has an advantage with the moderator that Trump is least likely to assail on those grounds.

Reason two: the interruptions and knee-jerk accusations have not worked. They have generally harmed whichever candidate has looked more reactive and less calm under pressure. In this debate, both Trump and Clinton need to show they can be presidential at the moments it counts the most. Now, will that force them to be presidential? We admit, it has not always done that in the past. But watch for this.
Count the number of issues

In a campaign that has left many voters wondering not just how to vote, but if to vote, look to see how many issues the candidates seriously discuss. While this may not tell you who will win on November 8th, it will be important in revealing the state of current American politics.

Do the candidates pivot immediately from tough issues questions? Or do they lay out serious plans? Do they speak in generalities about those plans, or do they offer real detail?

All of this should matter to voters, and even if it is eclipsed by the strange gravitational forces of this campaign, it may matter in what it says about the level of discourse that begins the next presidency.