EVANSTON—Gary Harris scored 14 points and No. 4 Michigan State beat Northwestern 54-40 on Wednesday night for its ninth consecutive victory.The preseason favorite to win the Big Ten, the Spartans (16-1, 5-0 Big Ten) continue to roll along, although it was hardly an easy night for them. They overcame a sluggish start and pulled away down the stretch even though they struggled in a big way from the outside.They were 2 of 16 on 3-pointers with Harris missing all six and Keith Appling going 0 for 3. Harris did have four steals, and Appling managed to score 11 points.Branden Dawson, fighting an illness, had 11 rebounds and three blocks, and the Spartans came away with the win even though they were missing one of their top players in Adreian Payne. The 6-foot-10 forward sat out his second successive game because of a sprained right foot, but Michigan State had enough to get by in this one.Tre Demps did his best to keep Northwestern (8-10, 1-4) in the game, scoring 10 of his 12 points in the second half, but leading scorer Drew Crawford never got going. He managed just six points with Denzel Valentine guarding him most of the game, and the Wildcats came up short after beating then-No. 23 Illinois on Sunday night to give new coach Chris Collins his first Big Ten victory.They haven’t knocked off a top five team since they took out fourth-ranked Michigan State on Jan. 27, 1979.Coming off back-to-back overtime victories against Ohio State and Minnesota, Michigan State probably could have used a breather. The problem was the Spartans had trouble sustaining a run.They looked like they were poised to put this one away after Travis Trice nailed a 3 and Matt Costello scooped in a reverse layup to make it 40-31 with 11:36 remaining. But Demps answered with a basket for Northwestern.It was 44-37 when Alex Gauna banked in a shot to start a six-point spurt that gave the Spartans a double-digit lead.Harris hit two free throws and stripped Demps, leading to two more foul shots for Appling that made it 50-37 with 4:59 left, and the Spartans hung on from there.