Donald Trump
Donald Trump, pictured at a rally against the Iran nuclear deal on Wednesday, Sept. 9, 2015, in Washington, will appear on the "Tonight Show" Friday. Chip Somodevilla/Getty Images

Friday night is not usually reserved for appointment television, but this week might be an exception. Donald Trump, the polarizing front-runner in the Republican presidential race, will be a guest on "The Tonight Show" Friday, and whether things get serious or downright silly, the appearance should be one not to miss.

For host Jimmy Fallon, the pressure will be on to make the visit count as Trump's latest controversy, surrounding comments he made about fellow Republican candidate Carly Fiorina, looms over the interview, not to mention the high bar set by new competitor Stephen Colbert's emotional "Late Show" interview with Vice President and potential 2016 Democratic candidate Joe Biden Thursday.

Here are four controversial topics Fallon could bring up in the highly anticipated Trump interview:

1. Carly Fiorina Comments

Trump is in hot water this week over some disparaging and arguably sexist comments he made about former Hewlett-Packard CEO Fiorina in an interview published by Rolling Stone Wednesday.

"Look at that face!" Trump told the magazine's reporter while watching Fiorina on TV. "Would anyone vote for that? Can you imagine that, the face of our next president. I mean, she's a woman, and I'm not supposed to say bad things, but really, folks, come on. Are we serious?"

Despite protests from Trump that he was referencing Fiorina's "persona," not her physical appearance, the media and Republican leaders have taken him to task for the comments. Will Fallon address the controversy? The appearance will be one of Trump's first appearances since the story broke, and it could feel like there is an elephant in the room if the comments do not at least get mentioned.

2. Immigration

When Trump entered the race, he cited immigration above all other issues. Trump's hardline stance -- if elected he promises to deport more than 11 million undocumented immigrants and build a wall on the U.S.-Mexico border -- has earned great attention and a following, as well as intense criticism. Univision anchor Jorge Ramos was briefly ejected from a campaign event in August while trying to confront Trump on his immigration plan's specifics. Will Fallon press Trump on the issue? The "Tonight Show" could be an opportunity for Trump to address critics and regain some favor among voters he has insulted with his anti-immigration rhetoric.

3. Debate

The easiest way for Fallon, who is not known for getting too serious in his interviews, to parse politics with Trump would be to discuss the Republican debate on CNN, which airs Wednesday. The topic allows Fallon to discuss the campaign without getting too deep into specific issues. Fallon brought the topic up with New Jersey Gov. Chris Christie in August and he may do the same here. Besides, Trump got even more publicity by clashing with debate moderator Megyn Kelly after the first debate on Fox News, and it would be interesting to hear his mindset going into the second debate.

Watch Jimmy Fallon discuss the debate with Chris Christie below:

4. Fun and Games

All right, this one might be cheating. Fun and games may not be controversial, but it is what Jimmy Fallon does best. If the host, who may lack the polticial acumen to go toe to toe with Trump on the issues, avoids serious topics, the interview could end up being an opportunity to humanize the candidate with some classic "Tonight Show" mayhem. Will Fallon bust out his Trump impression? Will he rope the candidate into a game of word blurt or a lipsync battle? Fans will have to wait to find out.

Watch Jimmy Fallon impersonate Donald Trump on "The Tonight Show" below: