The moment has arrived.

This is the biggest and most eagerly awaited showdown the world’s seen since Muhammad Ali and George Foreman’s Rumble in the Jungle, 42 years ago.

Only Trump-Clinton has every potential to even more brutal, and way more historic.

The two least popular candidates in the history of US presidential races going head to head for the first time in what many believe is a winner-takes-all encounter.

The stakes could not be higher or more dramatic.

The two least popular candidates in the history of US presidential go head to head tonight in what many believe is a winner-takes-all encounter. The stakes could not be higher

Foreman, famously, wielded what he called his ‘Anywhere’ punch.

When a bemused Ali asked his training team exactly what that was, he was told: ‘Anywhere it hits, it breaks something.’

For Foreman, read Trump - a giant bear of a man whose instinctive response to any confrontation is to unload (verbal) punches of unbelievable ferocity.

Clinton’s dilemma is whether to stand toe-to-toe and trade those punches or do what Ali did that night in Zaire and soak them up for round after round before dancing off the ropes to deliver a stunning knock-out.

Her problem is I don’t think either of those strategies will work.

As we saw in the Republican primary debates, Trump is a formidable debater who likes nothing more than people either taking him on, or taking his blows.

He will be in his absolute element tonight.

Trump is a formidable debater. This is the ultimate reality TV with 100 million viewers and Trump is a reality TV superstar

There’s nothing this swaggering, cocky, publicity-ravenous, charismatic billionaire could possibly love more than 100 million people tuning in to watch him perform on TV.

This is the ultimate reality TV and Trump is a reality TV superstar.

Further, Trump has little to lose.

Nobody expected him to get this far and his brand is now ten times bigger and more valuable than it was a year ago.

If he doesn’t win in November, he can simply to back to his day job, only considerably more globally famous than he was before, which for a man who markets his brand around the world is one big massive KER-CHING!

Clinton, by contrast, has everything to lose. She’s a career politician for whom thiselection represents either the thrilling culmination of an entire lifetime’s work or the humiliating nadir of 40 years working in Washington.

If she loses to a bombastic ‘lightweight’ political outsider like Trump, she’s finished in US politics. She knows it, we all know it.

So all the pressure is on her tonight.

Cinton’s the favourite, the candidate who most of the ‘smart crowd’ on America’s East and West coasts have long assumed has this election in the bag.

Only she hasn’t.

Latest polls show this is now a neck-and-neck race, with Trump’s popularity surging at just the right time for him and just the wrong time for his opponent.

He has the momentum, while she has the hanging noose of her recent health problems.

Clinton, seen here Sunday, has everything to lose. And one coughing fit on stage, or a momentary faint-like wobble under those hot lights and her hopes could be over

One coughing fit on stage, or a momentary faint-like wobble under those hot lights where they will be standing for 90 minutes, and it would be curtains for the Clinton presidency.

Call it unfair, call it sexist, call it what you like.

But this is modern, gladiatorial politics at its most brutal and expect no mercy from either Trump or the American electorate if Clinton shows any sign of physical weakness.

The other major issue for Clinton is what tone to adopt.

There’s one new statistic that should fill her with horror.

Trump is now leading her among non-college-educated white men by a staggering 59 points, according to the ABC News/Washington Post poll.

I’ve long thought that America’s white working class men would decide this election.

Trump speaks almost exclusively to them and for them.

His whole strategy has been focused on persuading these men that he is their champion, their saviour, their Robin Hood.

And this strategy has so far been spectacularly successful.

I’ve got no doubt Hillary will come over tonight as better briefed, more intellectual, more politically experienced.

But that might just serve to confirm her in the minds of those white, working class men as precisely one of those smug, patronising Wall Street supported Washington elite politicians they loathe and directly blame for a lot of their problems.

Trump won’t change. He never does.

I confidently predict that when the actions starts at 9pm ET, we’ll see the same intimidating, swaggering, zinger-firing presence he’s been for his entire campaign and indeed his entire business life.

He’ll vociferously hammer home all the key messages that have resonated so powerfully with his key target audience in states like Pennsylvania, Maine, Ohio and Florida: the wall, the Muslim ban, the disintegration of ISIS, defending the 2nd Amendment and bringing jobs back to America.

The problem for Clinton is what the hell she does about it.

If she viciously attacks him for those things, the white working class men will hate her even more for it and feel even more determined to vote for Trump.

When the actions starts from behind these dual height podiums, we’ll see the same intimidating, swaggering, zinger-firing presence he’s been for his entire business life. The problem for Clinton is what the hell she does about it

If she doesn’t viciously attack him for those things, she risks deterring her already unimpassioned own Democrat voters from coming out for her in the numbers she needs.

There’s no easy solution but my advice to Hillary is borrow a more traditional Muhammad Ali style than the one he used to beat Foreman: float like a butterfly, sting like a bee.

If she can dance around Trump’s relentless haymakers, looking and sounding cool, calm, collected and presidential, and all the while keep stinging him with irrefutable, damning fact-checking jabs of logic, then she can win comfortably on points.

Especially if in the process she succeeds in making him look small and stupid.

That will give her a huge lift heading into debates 2 & 3.

But Trump’s a highly competitive man and now he’s got this far, The Donald will be desperate to finish the job.

As he once told me: ‘You gotta win, that’s what it’s all about. You know, Muhammad Ali used to talk and talk, but he won. If you talk and talk but you lose, the act doesn’t play.’

So I expect him to come out swinging tonight and do what he promised to do: take Hillary Clinton down.

The big question is can she handle him?

Or will she be steamrollered by the Trump Train, like the other 17 Republican candidates?

By 10.30pm ET tonight, we’ll know the answer.