Not since the invasion of Normandy has a national event been considered more crucial to the outcome of a strategy than the first presidential debate between Hillary R. Clinton and Donald J. Trump tonight.

For weeks now, pompous pundits have been weighing in with advice for both candidates.  Nobody knows whether these "experts" have ever so much as stood on a debate stage, but apparently that's not a critiquing criterion.

Panels on the subject begin with a question like "What do Hillary Clinton and Donald Trump have to 'do' in the debates?"  Well, for starters, they have to stand up for 90 minutes.  This task may prove harder for Hillary than for her adversary.  On the other hand, The Donald may find it tough to stand up to the salvos of a more seasoned debater.  And, of course, neither contender can stand the other.

This animosity only heightens anticipation.  Viewers are switching from Monday night football not to observe a love fest.  They will most certainly expect some blood to be spilled on the political gridiron.  Once the game kicks off, neither player will be permitted to take a knee.  We'll look for tackles and touchdowns.  And while this contentious bit of political entertainment comes free of charge, viewers will nevertheless demand their money's worth.

Hence the advice about how the candidates can put it all together – from the same crowd of critics, incidentally, who will pull them all apart afterward.  Doesn't it occur to these sages that putting pressure on both presidential wannabes may not be the wisest thing to do?  But politics is a blood sport, and the debates are like the playoffs.  On Election Day, only one of the candidates will go away with the winner's trophy.

The high volume of advice from talking heads can be boiled down to a few common caveats for each candidate.  Donald Trump has gotten the lion's share of admonitions, because, according to the election scene gurus, this first debate will be his make-or-break moment.  Presumably, if he doesn't "pull it off," he might as well pull out of the race.

On the other hand, everyone seems to agree that the bar for Trump has been set very low.  I'm not sure why this is, since he has managed to catapult his candidacy into a neck-and-neck battle with his more experienced opponent.  By now he has figured out how to speak forcefully before various groups, most often before large groups of well-wishers.

But a debate is very different from a rally.  The teleprompters will be gone, and so will the wildly supportive audience.  Those attending the debate venues are advised not to express any enthusiasm for either candidate.  This rule, however, can prove as effective as the designation of a mall as a "gun-free zone."

Still, in a debate environment, Trump will no longer find himself basking in the presence of partisans, and he will miss their energizing feedback.  Certainly, nobody would accuse the debate moderators of being plucked from the infamous basket of deplorables.  In spite of these negatives, Trump's main challenge will be to somehow look and act "presidential."

The Donald may have excelled in the Republican primary debates, where he shared the stage with as many as 14 other contenders, but he will now find himself under greater scrutiny, sharing the spotlight with only one adversary , who is determined to annihilate him with her political savvy.  The worst threat, according to those in the know, is that she will try desperately to get under his thin skin.

So what advice do the political veterans have for the beleaguered Republican standard -bearer?  Basically this: Stay calm and carry on.  Keep focused and on message.  This would be far easier if only he knew the questions in advance!

Then there is Hillary.  She didn't have to face the same ordeal during her primary debates.  In fact, ironically, the only thing Secretary Clinton had to do in those performances was to keep her cool and seem credible – the same advice that is now being given to her Republican challenger!

Even at that, Hillary had some tense tussles with Bernie Sanders, especially in her final primary debate.  But she had the advantage of knowing from the start that she was the indisputable presumptive Democratic nominee.  As a result, the debates did not matter all that much.  Now they do.

The outcome of this presidential scuffle could well come down to two critical issues: knowledge and temperament.  Hillary's "job" is to show Americans that Trump is lacking in both.  A lot has been said about how she intends to goad her opponent into losing his famous temper.

But if in so doing she opts to examine Trump's baggage – both personal and professional – he may well decide to crack open hers.  The debate stage could become figuratively littered with the dirt of foundations, deals, debts, and defaults, not to mention The Donald's marriages and Hillary's handling of Bill's bimbos.  Voters may insist they want candidates to stick to the issues.  But we're only human – and we hate being bored.

As for Hillary, one wonders if she's really clever enough to insult Trump into bad behavior.  He's brash; he's blunt; he's not always wise.  But he certainly isn't stupid.  Hillary may be better off concentrating on the improvement of her own delivery woes: a shrill, faltering presentation and a sanctimonious tone that leaves a lot of listeners cold.

Still, she has been gushing about how she cannot wait to debate Donald Trump.  Bring it on!  Back in 2008, Joe Biden may have had the same cocky anticipation before he faced Sarah Palin in their only vice presidential debate.  Afterward, the omnipresent critics declared the contest a tie, which translated into a Palin win.

As soon as the debate ends, the rhetoric will switch to Tuesday morning quarterbacking.  Barring something bizarre, the event will likely pass into memory.  And having been there, the audience for the second presidential face-off will be much diminished.  If the anticipated fireworks fizzle, even the pundits will have to find some other place to park their advice.