EVANSTON, ILL. ? Northwestern clamped down on Wisconsin with a matchup zone defense that threw the Badgers’ timing off and kept star guard Devin Harris from taking over the game.

“That’s the best defensive game we’ve played all year. That was obvious with the emotion and all the loose balls,” Northwestern’s Jitim Young said after the Wildcats’ surprisingly lopsided 69-51 victory Saturday over the No. 14 Badgers.

“Everybody made shots and we played a great all-around game.”

The loss knocked Wisconsin (15-4, 6-2) out of first in the Big Ten Conference. Michigan State took over the top spot with its win over Ohio State.

Northwestern (9-11, 4-5) shocked the Badgers with a 34-11 run over the final 13:30 of the opening half — including a 15-0 spurt that had Welsh-Ryan Arena rocking — and opened a 17-point halftime lead.

Fans rushed the floor after the victory, their second over a ranked team in less than a month. They beat then-No. 25 Illinois Jan. 14.

Harris, coming off a career-high 38-point performance against Minnesota, scored 16 but shot just 4-for-18 from the field. Zach Morley added 15.

“Harris was frustrated the whole second half,” said Vedran Vukusic, who led the Wildcats with 18 points.

How could he tell?

“By his facial expressions,” Vukusic said.

“The shots were there, they just didn’t fall tonight. I mean I’m not going to score 30 points every night,” Harris said.

“We had good shots at the basket. The perimeter game was not the best and we should have gotten the ball inside more. But they played an extremely smart game and got what they wanted out of their offense.”

Young added 17 points, and the Wildcats actually got more than they expected offensively from Davor Duvancic, who hit four three-pointers — three of them during Northwestern’s huge first-half surge. He’d made just 12 three-pointers all season entering the game.

In Northwestern’s last two practices, the 6-foot-8 Duvancic shot about 500 three-pointers. And Saturday his work was rewarded as he hit his first three.

“They hit some big threes,” Wisconsin coach Bo Ryan said. “That’s three points a possession and it’s hard to get it back. That’s how it got away from us.”