The highlight of the first day of the 2017 NCAA tournament was Northwestern’s first-ever tournament win. But the Wildcats’ victory was possible only because of one of the biggest gaffes in March Madness history.

Up one with around 15 seconds left, Vanderbilt’s Matthew Fisher-Davis fouled Northwestern’s Bryant McIntosh. McIntosh went to the line, sunk two free throws and the Wildcats pulled out the win. Fisher-Davis, who thought his Commodores were down one, later admitted it was a “dumb-ass foul.”

The foul is far from the most costly blunder in NCAA tournament history, but it is up there with some of the worst. Here’s a look at the top six boneheaded plays over the years:

6. Pittsburgh-Butler turns into comedy of errors (and fouls)

Andrew Smith put Butler up one on top-seeded Pittsburgh with 2.2 seconds left in a second-round game in 2011. The sequence that followed featured two candidates for this list, with the second overshadowing the first.

With no timeouts remaining on either side after Smith’s layup, Pittsburgh inbounded the ball to Gilbert Brown streaking up the left side of the floor. Brown let the ball bounce, so Butler’s Shelvin Mack tried to make a play on it. He fouled Brown, and gifted him a chance to win the game.

Brown, however, missed the second free throw. Matt Howard corralled the rebound for Butler, and Pittsburgh’s Nasir Robinson foolishly contested him for it. In doing so, he fouled Howard 90 feet away from the basket. Howard walked the length of the floor, made one of his two free throws, and the ninth-seeded Bulldogs pulled off the upset — their second of five wins on the road to the national championship game.

5. VCU fouls 3-point shooter up four

VCU led Stephen F. Austin by four points late in a first-round game in 2014. With five seconds to play, Thomas Walkup found Desmond Haymon on a kick-out. All VCU had to do was let the shot go up, inbound the ball with three seconds left, and take care of business at the free-throw line. Instead, JeQuan Lewis did the one thing he couldn’t do. He flew out to the shooter and fouled him. Haymon made the shot, made the free throw and Stephen F. Austin won in overtime.

4. Vanderbilt fouls up one

Vanderbilt erased a 15-point deficit, and led Northwestern by one on a Riley LaChance layup. The shot clock was turned off. Vandy needed one stop to survive and advance. So it… fouled?

The foul wouldn’t have been the worst decision if it hadn’t been on McIntosh, an 86 percent free-throw shooter. Fisher-Davis said after the game that not only did he blank on the score, he saw Vanderbilt coach Bryce Drew pointing to McIntosh to instruct Fisher-Davis to guard the Northwestern player and thought Drew was telling him to foul.

Fisher-Davis’ teammates had his back, though. After all, he had scored a team-high 22 points and led Vanderbilt’s second-half comeback.

3. Phi Slama Jamma forgets to box out

Houston’s failure to box out Lorenzo Charles in the 1983 national championship game isn’t an inexplicable error, but it was as costly as any on this list. With the title game tied at 52 with five seconds remaining, NC State’s Dereck Whittenburg picked up an almost-errant pass near midcourt, turned and heaved a shot toward the rim. It was well short, but Houston’s players left Charles unaccounted for right by the rim. Charles finished the play as if it were an alley-oop right before the final horn, and Jim Valvano went sprinting across the court, looking for somebody to hug.

2. Chris Webber’s timeout

Webber and the Fab Five were in their second consecutive national title game in 1993. With 12 seconds left and North Carolina leading Michigan by two, Webber rebounded a missed free throw, got away with a travel and brought the ball up the court. With 11 seconds left, he found himself in a trap on the right side of the court, so he turned to call a timeout.

There was one problem: Michigan didn’t have any timeouts left.

The Wolverines were penalized with a technical foul, which effectively ended their hopes of mounting a late rally.

1. Fred Brown throws away the title to North Carolina

Michael Jordan’s jumper with 17 seconds remaining in the 1982 national title game gave North Carolina a one-point lead, but Georgetown still had the ball with a chance to win the game. Fred Brown dribbled up the court, picked up his dribble and looked for a pass. Out of the corner of his eye, he saw a player at the top of the key and flipped the ball in his direction …

Unfortunately the player was North Carolina star James Worthy. The turnover sealed the game for the Tar Heels.

More March Madness coverage from Yahoo Sports:
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• Perfectly awful: Here’s the worst NCAA tourney bracket
• Former President Obama has two big mistakes in his women’s bracket