Keith Appling scored 16 points and Gary Harris added 12 to lead No. 10 Michigan State past Northwestern, 71-61, on Sunday.
Adreian Payne added 11 points and Derrick Nix finished with 10 points and six assists for the Spartans (24-7, 13-5 Big Ten), who will have the third seed and a first-round bye in the upcoming Big Ten tournament. Michigan State will face the winner of Iowa and Northwestern on Friday.
Kale Abrahamson scored 16 points and Alex Marcotullio had 11 for the Wildcats (13-18, 4-14 Big Ten).
"I thought we played how we wanted to play, but you have to knock down some shots," Northwestern coach Bill Carmody said.
Northwestern, which will have the 11th seed in the conference tournament, will face sixth-seeded Iowa on Thursday. The Wildcats dropped both meetings with the Hawkeyes this season.
Alex Olah's dunk tied the game at 53-53 with 5:43 left, but the Spartans took over from there, outscoring Northwestern 18-8 the rest of the way.
Nix got things started with a layup nearly 30 seconds later and Branden Dawson sunk a pair of free throws to give MSU a four-point edge.
Appling scored the next four points, including a highlight reel slam with 1:40 left. Appling shook a defender at the top of the key and skyed to the rim before ferociously slamming it through the hoop.
Payne's free throws made it a 10-point game, 63-53, but the Wildcats wouldn't go away.
Marcotullio added a quick layup and, following a pair of Appling free throws, Abrahamson buried a trey with 41 seconds left to make it 65-58. Northwestern couldn't get closer than eight the rest of the way, though, as Spartans won their second straight game.
"You have to win tight games too," Michigan State coach Tom Izzo said. "When it came down to it, we started getting the ball back inside and we did the things that we had to do. That's going to do well for us in the tournament."
MSU held a 19-7 lead near the midway point of the first half and led 33-26 at the break.