"Eight days after Mitt Romney slapped a half-nelson on President Barack Obama," the peculiarly American version of presidential "tag-team wrestling" continues on Thursday, says Jim Galloway at The Atlanta Journal-Constitution. Vice President Joe Biden and challenger Rep. Paul Ryan (R-Wis.) "climb into the ring this evening to give their principles a breather," and like wrestling, "don't expect the encounter to be neighborly." We've laid out the challenges Biden and Ryan face in their first and only vice presidential debate. Here's what you need to know about what's being billed as Round 2 of the Obama-Romney "slugfest":

When is the debate, and how can I watch it?
The debate starts at 9 pm (ET) and lasts 90 minutes. The Biden-Ryan face-off, at Centre College in Danville, Ky., will be aired live on all four networks — ABC, NBC, CBS, and Fox — and the major cable news channels: CNN, Fox News, MSNBC, Univision, and CNN Español, among others. It will also be live-streamed on numerous websites. (GigaOm has a comprehensive list of where to watch it online and on mobile devices.)

Who's the moderator?
Martha Raddatz, the senior foreign affairs correspondent for ABC News. Conservative website The Daily Caller tried to make hay out of Obama's attending her 1991 wedding, as a guest of her now-ex-husband Julius Genachowski, who was on the Harvard Law Review with Obama. But the article "failed to make a major impact," says Politico's Dylan Byers — perhaps, notes CNN's Candy Crowley, because it was so obviously an attempt at "playing the refs." (Crowley is moderating next week's presidential debate.) Ryan's spokesman said the GOP campaign has "no concern" about Raddatz. 

Is there a theme to the debate?
No. According to the Commission on Presidential Debates, it will "cover both foreign and domestic topics," which leaves Raddatz an unlimited number of subjects to choose from. There are only nine slots, though, note Jason Linkins and Elyse Siegel at The Huffington Post, and "with so many domestic policy topics left untouched in the first presidential debate, and foreign policy encroaching at the veep debate, chances are viewers are going to be left wanting more." The bulk of the issues will almost certainly be domestic, but remember, Raddatz has "walked the foreign policy beat for the entirety of the past four years," so expect at least one question on Libya, Iran, or Afghanistan. 

What's the format?
Compared with the Denver presidential debate's, um, loose format, the Danville showdown will be positively regimented: There will be nine segments of about 10 minutes each; each candidate will have two minutes to respond to Raddatz's question, and she will use the remaining six minutes to foster discussion on the topic.

Who's favored to win?
Ryan. Voters expect the 42-year-old congressman to outshine Biden in at least three polls — by a margin of 55 percent to 39 percent (CNN/ORC International), 46 percent to 30 percent (Zogby), or 40 percent to 34 percent (Pew) — and no poll forecasts a Biden win. That is probably good news for the vice president, since it sets a pretty low bar. But Ryan has been rigorously preparing for the debate since Romney tapped him as his running mate in early August.

Do VP debates even matter?
The conventional wisdom is that no, vice presidential debates are mostly for sport, or, at best, a chance for the public to meet the men who will be a heartbeat away from the presidency. But that sells them short, University of Pennsylvania's Kathleen Hall Jamieson tells The Daily Beast. As in 2004, when Vice President Dick Cheney's strong performance helped President George W. Bush recover from his weak first debate against Sen. John Kerry, the VP showdown "can be an interlude which changes the present dialogue about the momentum of the campaign." But if you look back, says Dan Amira at New York, newspapers say that same thing every four years. So will the Biden-Ryan showdown "be the one that finally makes a huge difference?" Anything could happen, "especially when Joe Biden is involved" — but don't bet on it. Besides, as political scientist Jonathan Bernstein notes, this year's debate has its share of competition for viewers. The MLB playoffs — Yankees-Orioles (Game 4) and Tigers-A's (Game 5) — and an NFL matchup of the Pittsburgh Steelers and Tennessee Titans are all on at the same time.

Sources: The Atlanta Journal-Constitution, CNN, The Daily Beast, GigaOm, The Huffington Post, New York, Politico (2), Presidential Election News, The Wall Street Journal, The Washington Times 

Read more political coverage at The Week's 2012 Election Center.