Contenders should watch their backs

March Madness wouldn’t be March Madness without the excitement of those early upsets in the NCAA Tournament.

The 68-team field won’t be announced until Sunday, but it’s a safe bet one or more high seeds will get bounced early.

Purdue was a 23 ½-point favorite when it went out in the first round to No. 16 seed Fairleigh Dickinson last year — another in a line of tournament clunkers for the Boilermakers. Maybe it was because Purdue’s guards couldn’t make shots. Maybe Fairleigh Dickinson’s small lineup bothered the Boilermakers.

Kihei Clark’s memorable bad pass set up JP Pegues’ winning 3-pointer in No. 13 Furman’s upset of No. 4 Virginia last year, but the matchup did the Cavaliers no favors. Furman plays at a high tempo and spreads the floor. Virginia goes slow and its defense had difficulty guarding the perimeter, allowing Furman to stay in the game.

“The style makes the fight in how some of these things can happen if your strength combats the other team’s weakness and the other team is one of those higher seeds. That’s where you run into trouble,” said Field of 68 analyst and TV commentator Terrence Oglesby.

The odds of various teams winning the national title are fun to consider — as of Tuesday, injury-riddled blueblood Kansas is a 35-1 longshot, according to FanDuel Sportsbook, while San Diego State is 75-1 a year after crashing the national title game. Different season, different team.

Here are some projected high seeds that could be on upset alert the first weekend of the tournament:

Alabama

Coach Matt Painter and Purdue know how dangerous the early rounds of the NCAA Tournament can be for an elite team, having lost to 16, 15 and 13 seeds the last three years.