Michigan State missed enough shots in the first half to let Northwestern stick around.
Then, the fifth-ranked Spartans started making shots.
Durrell Summers had a season-high 24 points and 10 rebounds, leading Michigan State to a 79-70 win over Northwestern on Saturday night.
Kalin Lucas scored 23 points, had four assists and no turnovers, Draymond Green had nine points, 11 rebounds and four assists, and Delvon Roe scored 13.
``That was one of the more complete games we've played,'' coach Tom Izzo said.
The Spartans opened the second half with an 18-4 run that included Chris Allen's spectacular slam dunk.
``That really was the game,'' Wildcats coach Bill Carmody said. ``It was like bang.''
Michigan State led by just two at halftime following six lead changes and four ties after shooting 38 percent and missing 10 of 11 3-pointers.
The Spartans (19-3) are off to their first 9-0 start in Big Ten play, but their streak will be put to a test Tuesday night on the road against No. 16 Wisconsin.
``Wisconsin always plays us tough,'' Summers said. ``I haven't won up there.''
John Shurna made six 3-pointers and scored a career-high 31 points for the Wildcats (14-7, 3-6).
``I'd rather not talk that much about it because it's a team game and we lost,'' Carmody said. ``It's great, but when you come here, you come to win.''
Shurna's teammates made that tough. He had 20 points midway through the second half; the rest of the Wildcats combined for just 19 at that point. Michael Thompson made just two shots and finished with seven points - half his average.
``It was a key,'' Izzo said. ``Thompson has been playing well.''
Raymar Morgan had been, too, missing only one of 15 shots in the previous two games - a pair of one-point wins on the road against Michigan and Minnesota. But he fouled out without a point on an 0-for-5 night.
Summers has been inconsistent throughout his three-year career, impressing NBA scouts with his jaw-dropping talent and befuddling those same people during games in which he is barely noticed.
``With some guys, you don't know what buttons to push and he's one of them,'' Izzo said. ``He hasn't even scratched the surface.''
The 6-foot-4 guard was at his best against the Wildcats.
``Durrell was dynamite,'' Izzo said.
Summers soared for alley-oop dunks to open each half against Northwestern's zone, made 3-pointers, pull-up jumpers and dunked in a half-court set late in the game when they were rallying.
``We started him off with a play we saw in scouting,'' Izzo said. ``We thought it would get him going.''
It did.
Summers shot 9 of 13 overall, making two 3-pointers. He entered the game making a career-low 43 percent of his shots.
``He hasn't shot the ball as well as he's capable this year, but he was very good tonight,'' Carmody said.
Summers' performance rivaled the 21-point, 11-rebound game he had in a win this season against Gonzaga, when he set a season high and broke his career mark in rebounds.
The junior from Detroit was held scoreless this season against Wisconsin and The Citadel, but might be showing signs of dependability. He was tough to stop one game after scoring 10 and grabbing 10 rebounds in Tuesday night's thriller over Michigan.
``When Durrell plays like that, it's great to see,'' Roe said. ``Coach is on him so hard in practice. To see him respond is tremendous.''
As dominant as Summers and the Spartans were at times, they couldn't put Northwestern away.
Drew Crawford made a 3-pointer with 2 minutes left, giving the Wildcats a second player with double digits in scoring and pulling them within eight points. Crawford and Jeremy Nash finished with 12 points each.
Shurna's layup made it 71-65 with 1 1/2 minutes left and that shot matched the previous career high of 29 he had Jan. 2 in a 21-point loss to Michigan State.
``We got a little sloppy at the end,'' Izzo said.
The Spartans, though, made enough free throws the rest of the way to avoid getting stunned by Northwestern at home for the second straight season.
