ST. LOUIS –- Denzel Valentine slammed his hand to the floor in frustration during a second-half timeout. On a few other occasions, Michigan State guards slapped the court in anticipation of a key defensive stop.

Problem was, the Spartans spent more time punching the hardwood than they did fighting hard on defense. And it led to one of the biggest upsets in NCAA tournament history.

The real punches mostly came from No. 15 seed Middle Tennessee. By the time Reggie Upshaw Jr. dunked and got fouled in the final minute to seal the 90-81 victory, Michigan State -- and most of America’s brackets -- didn’t know what hit it.

It was a lack of defensive intensity that did Tom Izzo’s crew in. From the get-go, the Blue Raiders were the aggressors, making their first six shots en route to an early 15-2 lead. They never once trailed.

Every single time the Spartans made a big play to make you think order would be restored, Middle Tennessee had an answer. Three-pointers were answered by and-1s. Defensive stops were followed by forced turnovers.

Seemingly every key Blue Raider had the game of his life, as all five starters scored in double figures, led by Upshaw’s 21. Michigan State let them get too comfortable on offense, lackadaisically closing out on shooters and getting beat by penetration. The Spartans came into the game leading the nation in 3-point shooting and ranking 11th in the nation in 3-point defense. They got beaten at their own game, as Middle Tennessee went 11-of-19 from beyond the arc and shot 56 percent overall.

Throughout the second half, Spartans players wore blank stares and confused looks, as if they couldn’t believe what was happening. It’s going to be a long offseason in East Lansing after the most painful loss in program history. Michigan State will have months to ponder how it let it all unravel.