We know the Barack Obama who will step up to the podium, but how many of the multiple Mitts will engage him on domestic policy in Denver two weeks from Wednesday?
All those hours of watching Romney in 2008 and 2011 yield so many possibilities.
Could it be the earnest I-wanted-the-President-to-succeed version he tried out briefly at the GOP convention?
Or the president-with-business-experience Romney loftily trashing Obamacare but getting bogged down on how he imposed a tax in his Massachusetts mandate?
Or a they-stole-my-lunch Romney who had to hire an “attack coach” against Newt Gingrich last year?
"There's two ways to look at this guy. One is that the glass is half empty,” said a Republican dean of public policy at the University of Massachusetts in 2007. “The other is that the glass is totally empty."
The conventional wisdom about the first presidential debate in 1960 is that Nixon looked unshaven and sickly compared to JFK, but in my memory more important was his attitude, a Uriah Heep blend of being oily and agreeable yet slyly combative.
Romney will avoid that error, but how will he otherwise deal with a Barack Obama who knows who he is, will politely but firmly press his case for reelection and, as he has shown on the basketball court, use his elbows in the clinches without getting called for fouling.
As the Romney campaign lurches on in increasing disarray, there are more and more signs of how badly overmatched he is.
The real danger for the President is overconfidence, but his campaign will be downplaying expectations over the next two weeks and prepping their man to bring his best game.