EVANSTON—Playing in wet and windy conditions, Northwestern was close to perfect. Godwin Igwebuike stepped up on defense, and Justin Jackson gobbled up the yards on the ground.That slow start for the Wildcats seems like a long time ago.Igwebuike had three interceptions and Jackson rushed for 162 yards, helping resurgent Northwestern upset Melvin Gordon and No. 17 Wisconsin 20-14 on Saturday.Trevor Siemian threw for a touchdown and also had a key block on Miles Shuler’s 16-yard TD run as the Wildcats (3-2, 2-0 Big Ten) earned their third straight win after opening with consecutive losses to California and Northern Illinois. ”I think we’re definitely playing with a lot more passion and a lot more physicality than we did earlier in the year,” coach Pat Fitzgerald said. ”I don’t have any issues with what we did early in the year, except for what we were doing on Saturdays.” The Wildcats also had a nice day on special teams, with Jack Mitchell kicking two short field goals and punter Chris Gradone handing over poor field position to the Badgers for much of the afternoon.Gordon had 27 carries for a career-high 259 yards and a touchdown, but Tanner McEvoy and Joel Stave combined for just 138 yards on 12-of-29 passing. It was Stave’s first appearance of the season after the 19-game starter struggled mentally with throwing issues. ”Obviously being competitors, both of us want to start and play every snap, but right now where the team is at, we can really benefit from both of us playing,” Stave said. Wisconsin (3-2, 0-1) had scored at least 20 points in 17 consecutive games for the second-longest such streak in school history. It was the first loss for the Badgers since they dropped their season opener to LSU. ”It appeared to me without seeing the tape that’s the worst tackling game we’ve had this season,” coach Gary Andersen said. The Badgers trailed 10-0 before Gordon had a 2-yard touchdown run on their first possession of the second half. Gordon had six carries for 75 yards on the drive, including a 61-yard run on his first carry of the period.Gordon has rushed for 140-plus yards four times this season. He is averaging 42.8 yards on his first carry of the second half through five games.Wisconsin then got the ball back, but Stave was intercepted by Jimmy Hall, and Shuler scored on a reverse on the next play. Siemian helped clear the way with a block on Joe Schobert. ”I think I kind of just got (in) his way just enough,” Siemian said with a grin. ”I wouldn’t even call it a block.” Stave, who replaced McEvoy late in the first half, also was picked off by Igwebuike in the end zone with 5:55 left in the game. He tossed a 19-yard touchdown pass to Kenzell Doe with 4:16 to go, but Wisconsin didn’t get the ball back until the final minute and Igwebuike put it away with another interception.The redshirt freshman became the first Northwestern player with three interceptions since Neil Little against Indiana on Nov. 10, 1973. ”I mean nobody saw it coming. I didn’t even see it coming,” said Igwebuike, who made his first career start with Ibraheim Campbell out with a hamstring injury. ”It really goes back to just preparation. I knew it was going to be my time to step it up this game with the injury to Ibraheim.” It looked as if Northwestern might be in for a long day when Gordon had a 58-yard run along the visitors’ sideline on his first carry of the game. The junior ran for 8 yards on third-and-1 on his second carry, becoming the 11th player in school history with at least 3,000 yards rushing for his career.But the Badgers’ first drive ended when Max Chapman hit McEvoy while he was trying to throw the ball to Alex Erickson, and Igwebuike picked it off in the end zone.Mitchell kicked a 22-yard field goal in the first quarter, and Siemian added a 5-yard touchdown pass to Dan Vitale with 3:38 left in the half.The 15-play, 80-yard TD drive featured two fourth-down conversions, including a 2-yard run for Warren Long and a clutch pass from Siemian to Shuler.Siemian was 11 for 21 for 133 yards at the break, compared to 24 yards passing for Wisconsin. With Gradone in the middle of a solid performance, four of the Badgers’ five first-half possessions began at their own 10 or worse.