With President Donald Trump and his amen corner at Fox News and various portals of the right so persistently attacking Biden's stamina and mental acuity, I anticipated that this could be the most crucial test for the former vice president.
While that still is true, Trump and his apparatchiks have so lowered the bar with their cartoon caricatures of Biden that they have done him an enormous favor. Biden doesn't need a perfect performance Tuesday night. He just needs a reasonably coherent and energetic one.
In belittling Biden, Trump has complicated his own debate prospects by promoting a presumption that he will mop the floor with "Sleepy Joe." For the President, a close battle won't do. He needs a knockout.
Without question, the stakes are high for both men, but the pressure to deliver weighs more heavily on Trump.
There are two approaches the President can take to shake up the race. One is out of character. The other is familiar.
The first would be to turn in a modulated and thoughtful performance that would cause the relatively small number of voters still up for grabs to look at him anew.
Trump will certainly try to change minds by stressing -- and, most likely, greatly inflating -- his accomplishments. While Biden leads in most categories, Trump retains a polling edge on who is best equipped to lead the economy. He might try to burnish this advantage.
But Trump's approval rating has been mired in the low- to mid-40s throughout his presidency, and his mishandling of the raging pandemic that has claimed more than 200,000 American lives hangs from his neck like the anchor from USS John S. McCain.
Voters were more willing before the virus to credit Trump with a strong economy and forgive his daily tweetstorms and squabbles. Now the cost of the President's character flaws has been made clear by his chaotic response to a virus he would sooner deny than confront.
And the idea that for 90 minutes Trump can contain his instincts to strike out wildly seems wildly improbable.
So assume that Trump's mission Tuesday night will be more to sow doubt about Biden than to remove doubts about himself.
Don't expect a lot of new material. Trump is basically a worn-out stand-up act. The lines are familiar.
He will try to bait the former vice president by calling him soft on China, and an aged and addled tool of a mob-coddling, police-hating, immigrant-loving left. Though he is the incumbent, Trump will try to portray himself as a force for change and Biden as an exemplar of a failed status quo in Washington.
For Biden, the considerable challenge will be to avoid chasing Trump down every rabbit hole or the urge to correct every falsehood.
Instead, he should want to force Trump to respond and defend.
The case against the incumbent is well known and widely accepted. Biden simply needs to hammer it and offer a vision of a better path forward.
In a perfect world, Biden would, at times, turn Trump's negative energy against him and, rather than engaging, address the country: "This is exactly what we've seen for the past four years, and we have paid a terrible price for it. The question you have to ask yourselves is, do you believe the next four would be different or better? That he will change? That he will grow?"
But, as we saw in his last primary debate against Bernie Sanders, Biden's debate engine can run hot and, challenged by Trump, he may not want to give the President any quarter.
If what results is a verbal brawl from start to finish, that might suit Biden just fine.
Elevated moments in contrast to Trump could pay big dividends and win critical acclaim. But feisty exchanges from the start to finish would definitively answer questions about energy and stamina and remove what is perhaps the only barrier left for Biden to clear.