The annual Big Ten-ACC Challenge was always supposed to have a game featuring two top-five teams. But the idea that Tuesday night’s top-five matchup is Michigan at Louisville, as opposed to Duke at Michigan State, is something I don’t believe anybody saw coming as recently as eight afternoons ago.

Let’s back up.

Eight afternoons ago, Duke was No. 1 in the Associated Press Top 25 poll while Louisville was No. 2, Michigan State was No. 3 and Michigan wasn’t ranked at all. So, yeah, Duke-Michigan State was set to be something special — and Michigan-Louisville looked like a perfectly reasonable undercard featuring the two teams that played in the championship game of the 2013 NCAA Tournament.

But then things got CRAZY.

Michigan State lost to a Virginia Tech team last Monday night that was picked 14th in the ACC. Then, last Tuesday night, Duke lost, as a 28-point favorite, to a Stephen F. Austin team that was ranked 264th at KenPom. Then, on Wednesday, Thursday and Friday, Michigan beat (in order) Iowa State, North Carolina and Gonzaga to win the Battle 4 Atlantis. And then, on Friday night, Louisville handled Western Kentucky, no problem, to remain undefeated. So now Michigan-Louisville is the top-five matchup.

The undercard is now the main event.

Louisville is No. 1 in Tuesday’s CBS Sports Top 25 And 1 daily college basketball rankings. Michigan is No. 5. And that Duke-Michigan State game is now something way less than what it could’ve/should’ve been.

Tuesday’s Top 25 And 1