In one ring was Sarah Palin battling comedian Tina Fey's TV impression of Sarah Palin. In the other was Joe Biden battling John McCain.
They both delivered somewhat uneven performances - but both "won" their individual bouts.
The question is - which one did more to carry his or her boss to victory on 4 November?
Mrs Palin's prerogative was simple: deliver your talking points and pivot to an attack on Barack Obama - regardless of what moderator Gwen Ifill was asking.
The results of this strategy were mixed.
Sarah Palin did manage to keep Joe Biden on the defensive in the debate
For one thing, Mrs Palin's repeated attempts to bait Mr Biden into making one of his famous "gaffes" or saying something "condescending" - she repeatedly sought to provoke his ire by pointing out instances (such as Iraq war funding, or the experience issue) where he and Mr Obama had disagreed in the past - did not succeed.
Not only did Mr Biden resist the temptation to charge her podium a la Rick Lazio, but he delivered crisp, clear ripostes that began with the words "That charge is not true" instead of, say, "Governor Palin is lying".
(The one time he said "Sarah," in fact, he immediately reverted to "governor".)
That said, Mrs Palin did manage to keep Biden on the defensive - especially on raising taxes - for substantial stretches of the debate. Always a good thing.
Her strongest moments came when pivoting from the topic at hand to some sort of folksy, emotive talking point.
When Ms Ifill asked whether we saw the "worst of Washington or the best of Washington... play out" in recent congressional jockeying over the bail-out bill, Mrs Palin detoured to the soccer field:
Palin turns on 'folksy' charm
"You know, I think a good barometer here... is to go to a kid's soccer game on Saturday, and turn to any parent there on the sideline and ask them, 'How are you feeling about the economy?' And I'll bet you, you're going to hear some fear in that parent's voice."
To practised ears, this sounded like a line that Mrs Palin had memorised and repeated.
But for voters who had only seen her fumbling through the Katie Couric interviews - or had only seen Ms Fey parodying her fumbles - Mrs Palin surely sounded clear enough, compelling enough and spoke enough common sense to seem like a competent public figure (as opposed to an incompetent caricature).
She ultimately pulled off this trick a couple more times: mentioning her "middle-American", "Joe Six-Pack" roots or admitting that it was time to stop "finger-pointing" and move past President Bush's "big blunders".
It was the main reason she exceeded expectations.
The problem for Mrs Palin, however, is that she often seemed to run out of talking points - at which point her answers would devolve into the confusing "blizzards of words" that ABC News interviewer Charlie Gibson recently endured.
Asked about the causes of climate change, for example, the Alaskan seemed unable to muster an intelligible response.
Palin proved that she's not an incompetent speaker - and prevented herself from becoming a perpetual punchline
"I'm not one to attribute every man - activity of man to the changes in the climate," she said.
"There is something to be said also for man's activities, but also for the cyclical temperature changes on our planet... What I want to argue about is, how are we going to get there to positively affect the impacts?"
This isn't to say Mrs Palin crashed and burned. She didn't.
Over the course of 90 minutes she undoubtedly sounded smart, savvy and spunky enough, often enough, to seem to belong on stage.
But there were simply too many of these "huh?" moments - especially near the end of the debate - to convince the 60% of voters who now say that Mrs Palin is not ready to lead the free world that they are wrong (and that John McCain is right).
On Thursday night Mrs Palin proved that she's not an incompetent speaker - and prevented herself from becoming a perpetual punchline.
But I doubt that she convinced many swing voters that she is qualified to assume the presidency at a moment's notice.
I think that this deficit rebounds to Mr Biden's - and by extension Mr Obama's - benefit.
Mr Biden didn't have a perfect night. His performance seemed to veer from muted to blustery, and it took him a while to find his footing.
Biden has an emotional moment
But he never seemed arrogant, condescending or chauvinistic. He never blathered on endlessly. And he certainly never put his foot in his mouth.
More importantly, Mr Biden did what he came to do - make a clear case against John McCain.
You may disagree with his arguments. Many will. But it's impossible to say he wasn't polite, persuasive and well-informed.
In fact, he even out-emoted Mrs Palin, telling his heart-rending story about raising two sons after his wife and daughter were killed in a car accident.
People are "looking for help", he said, choking up. "They're not looking for more of the same."
Ultimately, partisans will ignore the errors and find much to cheer in each candidate's performance.
But when it comes to the all-important swing voters, I suspect that Mr Biden may have the edge. Unlike pundits, undecideds don't have unique, finely-calibrated expectations for each candidate.
All-important swing voters told pollsters that Joe Biden won the debate
Unlike partisans, they are not preconditioned to support the politician who flatters their ideological biases.
They are just looking for the most plausible president - or in this case, vice-president.
Mrs Palin delivered a largely positive performance. But Mr Biden, I think, was more vice-presidential.
So far, the surveys seem to support this hypothesis.
CNN's "instapoll" gave the debate to Mr Biden, 51% to 36%, and 46% of undecided voters surveyed by CBS News agreed (21% thought Mrs Palin won).
Could these stats be wrong? Sure. But even if the voters ultimately decide that the Showdown in St Louis was a draw, it won't be enough to alter the basic contours of the race.
Right now, Barack Obama is up by an average of six points and breaking 50% in some polls - with only 33 days to go. A tie won't do the trick.
In other words, survival is all well and good. But it's a far cry from winning on election day.
This article was first published on Newsweek.com on Friday 3 October 2008.
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