Northwestern notched a big, NCAA Tournament-building win over Dayton at the United Center on Saturday. But it sure didn’t feel like one.

The Wildcats played a nearly flawless first half to build a seemingly insurmountable 40-17 lead. Then they collapsed in the second and almost blew it before making just enough plays to sweat out a 67-64 win over the Flyers.

“I thought the first half we played about as well as we could play, to be honest,” said head coach Chris Collins, who offered that fatigue played a role in Northwestern’s squandering its commanding lead in the second stanza. “We need (Dererk) Pardon back,” he said, referring to his injured starting center.

Sanjay Lumpkin, the "heart and soul" of the club, as Collins likes to say, scored 14 points and pulled down 14 rebounds to lead the Wildcats (9-2) in both categories before fouling out with eight seconds left. Scoochie Smith scored 18 to pace Dayton (7-3).

Here are our three pointers on the Wildcats’ harrowing win:

Northwestern put on a clinic in the first half..: Just like they did against DePaul, the Wildcats played a fantastic first half. They began the game on an 11-0 run and didn’t look back, going on a 15-0 tear later in the half to open up their 23-point bulge at the break. Five Wildcats scored at least five points, led by Lumpkin, Scottie Lindsey and Nate Taphorn with eight apiece. Northwestern’s suffocating defense harassed Dayton into 14.3 percent shooting (4 for 28) and held leading scorer Charles Cooke, who averages 20 points per game, to just one free throw. The Wildcats had 10 assists on their 15 first-half baskets and outrebounded the Flyers 27-14. Lumpkin may have played the best half of his career, with 11 rebounds to go with his 8 points. The Wildcats looked just as dominant against the Blue Demons a couple weeks ago, but Dayton is a much better team, making this run much more impressive.

…and then went into a panic in the second: Lumpkin hit a 3-pointer early in the second half to push the lead to 24, and then the Wildcats fell apart before hitting just enough baskets (just 6 of 22) and free throws (12 of 17) to win it down the stretch. The Flyers went on an epic 22-4 run to set up a harrowing finish, as they pulled to within 3 points twice in the final 10 seconds. Dayton canned almost half of its 3-pointers (7 of 15) in the second half and the Flyers' full-court press gave the Wildcats fits, forcing them into more turnovers (eight) than baskets (six) in the half. How bad was NU's offense? Over the last 10:18, Northwestern made just one field goal, a jumper by Bryant McIntosh, who scored 13 points and dished out five assists but committed a game-high eight turnovers.

This team needs to learn how to close out wins: Northwestern let potential signature wins slip through its fingers against Butler and Notre Dame earlier this season because of a failure to execute with the game on the line. While the Wildcats got the victory this time around, they didn’t do anything to alleviate any of those same concerns in the clutch. The Wildcats played aggressively and freely in the first half and then got tight in the second, as if they were playing not to lose instead of to win. Northwestern’s top two scorers, Vic Law and Lindsey, managed just four points combined in the second half. The Wildcats again showed an inability to break the full-court press, and even inbounding the ball was often an adventure. Several times, there just weren’t any Northwestern players that looked like they wanted the ball -- and their woes extended to the free-throw line where they missed nine shots (17 of 26) in the game. The Wildcats are capable of playing with any team in the country for stretches, but they still have a lot of work to do when the lead gets down to single digits in the second half.