By Kevin Connolly
BBC News, Missouri
Vice-presidential debates are races for also-rans - the American political equivalent of third and fourth place play-offs in the football World Cup finals.
Joe Biden and Sarah Palin avoided making any major slip-ups
They normally generate interest levels to match.
But Campaign 2008 has been different all along - and the battle of the bottom of the ticket was different too, in this year of firsts.
Democrat Joe Biden and his Republican counterpart, Sarah Palin, are political polar opposites and they inhabit very different cultural galaxies but they do have one thing in common; they are united by a flair for the kind of political slips that can shape the destiny of campaigns in which hundreds of millions of dollars have been invested.
We don't know the exact figures yet but tens of millions of Americans will have watched the full 90 minutes last night.
And one more statistic we'll never know - how many watched in the hope that Mr Biden would strike a couple of bum notes or that Mrs Palin, who has floundered in recent television appearances, would simply implode and take the whole Republican campaign with her.
Many viewers will have stayed on to the end, watching as you watch high-wire artists performing without a net, with a guilty fascination at the possibility that one might fall.
In the end, anyone hoping for a moment of train-wreck television would have been disappointed.
Mr Biden and Mrs Palin were both competent, if not exactly sparkling.
The highly restrictive format in which the moderator worked through a list of questions with very little interaction between the candidates and few supplementary challenges pretty much ensured that neither would be able to deliver a knock-out blow.
The unavoidable question on these occasions is simply "Who won?", and on this occasion it is particularly difficult to answer.
I'd be inclined to call it even, while noting that Mrs Palin perhaps exceeded expectations and even got a couple of cheeky digs in towards the end.
Having said that, Mrs Palin gave her supporters some anxious moments - particularly in the early part of the debate where she dealt with at least one question on the economy by ignoring it and offered a distinctly wobbly response on climate change - as though she couldn't quite remember the details of a hastily learned answer.
Most of the time though, it felt we were watching two over-rehearsed performances in parallel, in which both candidates will feel they got their messages across.
It started off stiff and awkward, with Mr Biden lavishing praise and name-checks on Barack Obama and Mrs Palin doing much the same thing for her running mate, John McCain.
Mrs Palin sought to appeal to ordinary American voters
There were lengthy dry exchanges on foreign policy and on the $700bn (£380bn) bail-out which is stalled on Capitol Hill at the moment, and in those passages, neither candidate really stood out.
Mrs Palin seemed particularly nervous at first, clearly mindful of the way in which her disastrous performances in recent network television interviews had dulled the lustre of her surprise selection as candidate for the vice-presidency and damaged the McCain campaign.
The woman who famously knows how to shoot a moose hasn't shot anything lately but herself. In the foot.
She settled comfortably enough into her core message - she is not a Washington insider and she is a rallying point for the America of "hockey moms and Joe six-packs" that lies beyond the Washington "beltway".
The most interesting part of the debate perhaps came when the two were effectively fighting over which of them most faithfully represents the world of blue-collar America where the millions of floating voters who will decide this election live.
She referred to her home town, saying: "We need a little bit of reality from Wasilla Main Street..." and he responded immediately with a reference to his "… all you got to do is go down Union Street in Wilmington with me and go to Kay's Restaurant…"
The stilted format didn't help the drama - perhaps the most effective dig of the evening came when Mrs Palin used one of the most quoted lines from the history of US debating, from the Reagan-Carter debate in 1980: "There you go again…"
Mr Biden had to avoid seeming patronising or overbearing
It probably scored a few points with Republicans, although perhaps that's not entirely fair to Mr Biden.
It was generally accepted in American politics that as an older man debating with a younger woman he couldn't afford to seem overbearing, confrontational or patronising.
He avoided those traps, but those ground rules made it difficult for him to land any scoring punches.
Mrs Palin grew in confidence as the evening went on, to the point where when the moderator Gwen Ifill tried to catch her out with a question quoting her previous views on the vice-presidency she dismissed them as a lame attempt at a joke - adding "and yours was a lame attempt at a joke too, because no-one got it".
The candidates were at their best at their most personal.
Joe Biden's voice caught momentarily as he recalled the days when he didn't know whether or not his other children would survive their injuries from the car accident in which his wife and infant daughter died.
Mrs Palin winked at her father in her audience when she announced that he was there and offered a "shout-out" to the third-grade class her brother teaches, offering extra credits for students who'd stayed up late to watch the debate.
On the whole, though, it was an evening of pitfalls avoided, rather than victories won.
Both sides will naturally claim victory, as you would expect, and both will feel they got some points across, but Mrs Palin's advisers - who have clearly worked hard to brief her in the last few days - will feel a sense of relief that they got their candidate through her biggest challenge.
She was never going to win the election for them tonight, but she could have lost it and she didn't.