He may have snarled a late "nasty woman" at his rival, but he never reached the vitriolic heights of the second clash, in which he called her a demon, with "tremendous hate in her heart".
To the soundtrack of a desperate last gasp, the "rigged" slogans have been the centrepiece of Trump's appearances all week, an extension of a narrative he has built since the start: the idea of a corrupt, insulated political-media machine; Trump as the fearless, independently wealthy outsider, fighting for the ordinary American against cosseted, self-serving establishment elites.
He clearly has a point, and for it's own good Washington DC should be listening.
But in declining to say that he would accept the outcome of the election, Trump has taken it up a notch, confirming his status as a personification of Thomas Hobbes' state of nature - nasty, brutish and short-fingered.
By signalling, in such a formal set-piece, to his most fervent supporters that his defeat could be a fix, he tipped petrol on flames.
The campaign that has plumbed some unimaginable depths could yet get altogether nastier.
If a week is a long time in politics, in this American presidential election it's a head-bending eternity.
Over the nine days between the last two debates, the headline deluge continued. Women came forward saying the Republican candidate had sexually assaulted them, taking the total to at least 10, with the candidate saying some of them were insufficiently attractive to warrant his attentions.
The Republican house speaker abandoned the Republican presidential candidate. A Democratic campaign consultant resigned after video emerged appearing to show him urging people to provoke violence at Republican rallies.
There's more. Among revelations from WikiLeaks was an account of a staffer for the Democratic candidate discussing a "quid pro quo" over the classification of a potentially damaging email in return for helpful agent placements.
The WikiLeaks boss, who is from Australia, had his internet cut off by Ecuador, in whose Embassy he lives in Britain, owing to concerns over interference in an election in America, which some reckon is enabled by Russia.
Oh, and the Republican candidate suggested his Democratic rival was on drugs. Normally such a claim would stop everything in its tracks. This time, Donald "sniff" Trump calling for pre-debate drug tests only raised eyebrows for a fleeting moment.
Responding to questions in Vegas about sexual assault, Trump alternated spluttered denials with declamations about Democrats inciting violence, as if flicking back and forth between two radio stations.
His problem, of course, is that he has spent the vast part of the campaign spouting implausible claptrap.
It is doubtful that him raising reasonable concerns over reports of a Democratic campaigner fomenting violence (albeit reports coming from a highly tendentious outlet), not to mention the "quid pro quo" email, would gain credence with undecided voters. He is the man-baby who cried wolf.
The state of the polls meant that the third debate should have been little more than a dead rubber - and that is in no way a commentary on either candidate's complexion. But in 2016, the most unpredictable year in western politics for a long time, nothing is to be taken for granted.
What if Brexit - remembering that almost all the polls predicted a vote to stay in the EU, and prediction markets had remain at more than 75 per cent - was just a dress rehearsal?
Notwithstanding the perils of hubris and the fact Trump has dubbed himself "Mr Brexit", Trump's decision to "keep you in suspense" about the vote was as good as an acknowledgement that he knows he can't recover.
He's lost, and he's a terrible loser. The question now is not bloody hell what happens if he wins, but bloody hell what happens when he loses.
In saying he may not accept the result on November 8, Trump is not merely suggesting we look out for a few dimpled chads.
His suggestion, utterly unsupported by evidence, that voter fraud is rife in America, is a red rag to any bull-headed supporters.
Such as Steve Webb, quoted by the Boston Globe this week saying he'd be heading to his local polling booth to conduct some "racial profiling. Mexicans. Syrians. People who can't speak American. I'm going to go right up behind them ... I'm going to make them a little bit nervous."
Dan Bowman told the same Globe reporter that if Clinton was announced as the victor, "I hope we can start a coup. She should be in prison or shot ... There's going to be a lot of bloodshed."
It's not just a handful of fanatics, either. Senior Trump adviser Roger Stone said in August that Trump should put his supporters "on notice that their inauguration will [invite] civil disobedience, not violence, but it will be a bloodbath ... We will not stand for it."
Perhaps it will not come to that. Perhaps it is all noise, a spasm of outrage, and Trump will show a little dignity on election night, conceding honourably, and heading off to focus on his new Trump-o-vision TV phenomenon, or whatever he's planning, and/or face sexual assault charges in court.
But as long as Donald Trump is keeping us in suspense, there is a real risk November 9 could be a dark day in American history.
