EVANSTON, Ill. -- Chris Collins didn't expect his team to score only 49 points in his first conference victory. Still, he wasn't complaining.

Tre Demps scored 11 points and made three late 3-pointers to lead Northwestern to a 49-43 upset of in-state rival No. 23 Illinois on Sunday night. Drew Crawford added 14 points and JerShon Cobb had 11 for the Wildcats (8-9, 1-3 Big Ten) in Collins' his first Big Ten win.

Northwestern had lost four straight overall and three in a row in conference play, but snapped both streaks thanks to its defense. Following a one-point loss to DePaul on Dec. 27 to end nonconference play, the Wildcats lost by 27 to Wisconsin, 23 to Michigan, and 26 to Iowa before beating Illinois and holding them to 28.1 percent shooting from the floor.

The Wildcats beat the Fighting Illini despite shooting only 37.2 percent from the floor.

"That was a special night for us. Obviously, thinking of getting my first Big Ten win I never thought my team would have only 49 points," Collins said. "I always liked to have 49 myself when I played."

No Wildcats player came close to that, but Demps helped them put away the victory.

After leading by as many as eight in the second half, Northwestern allowed Illinois to tie the game at 27 on Kendrick Nunn's layup with11:31 left. Demps, though, hit three 3-pointers in three minutes, the last giving Northwestern a 43-36 lead with 3:28 to go. Cobb's layup with 1:53 left gave the Wildcats a 45-36 advantage.

Illinois thought it cut the lead to 45-42 with 55.9 left, but Joseph Bertrand was called for charging, wiping out his basket. The Illini got to within 45-43 when Rayvonte Rice hit a 3-pointer with 15 seconds left, but Crawford hit two free throws with 14.3 seconds left and Northwestern finished the upset.

"I've been at the gym all day for the last two days and I was just waiting for a good look. When I hit the first one I got a good rhythm going," Demps said. "But the main thing was that my teammates believed in me."

No one on Illinois got much of anything going.

Tracy Abrams had 13 and Rice had eight for the Fighting Illini (13-4, 2-2), who have lost two straight after four consecutive wins.

Rice, who entered as the conference's leading scorer at 18.8 points per game, didn't get his first basket until there was 8:39 left in the second half. The redshirt junior guard was 2 of 11 from the floor and missed all five of his first-half shots. He had scored 19 points on 7-of-21 shooting in a 95-70 loss to No. 4 Wisconsin in Madison on Wednesday.

Northwestern held Illinois to a season low in points without junior guard Dave Sobolewski, who missed the game due to a concussion he sustained in practice.

"Shots didn't fall that guys normally make," Abrams said.

During their loss to the Badgers -- the Fighting Illini's most lopsided defeat of the season -- they shot just 31.6 percent from the floor and had just Rice and Bertrand score in double figures. That didn't improve much Sunday, when Illinois made 18 of 64 shots.

"I felt like we did not make enough plays on offense. I didn't feel like we were nearly aggressive enough. I thought we were way too tentative offensively," Illinois coach John Groce said. "We're going to have to figure that out pretty quickly. I feel like it's been that way now for a couple games."

Ranked for the first time since Jan. 14-20, 2013, Illinois got off to a slow start in the lone meeting between the in-state rivals this season.

The Illini shot 6 of 31 from the floor (19.4 percent) and missed all eight of their 3-pointers in the first half and trailed 22-15 at halftime. The 15 points were the Illini's fewest in a half this season and the second-fewest Northwestern has allowed over 20 minutes.

Northwestern couldn't pull away in the first half, shooting 33.3 percent. Despite that, the Wildcats were still able to give Collins an important win.

"It was amazing," Demps said. "Just to be in there with my brothers and to hug each other. It was a feeling like no other."