EAST LANSING, Mich. (AP) -- Just over a month after being held to single digits by an FCS team, Northwestern has solved a lot of problems offensively.
Justin Jackson rushed for 188 yards and two touchdowns, and the Wildcats moved the ball almost at will after a slow start, beating Michigan State 54-40 on Saturday night to hand the Spartans their fourth straight defeat.
Clayton Thorson threw for 281 yards and three TDs for the Wildcats, who rallied from an early 14-0 deficit. Michigan State (2-4, 0-3 Big Ten) is now mired in its longest losing streak in coach Mark Dantonio's 10 seasons at the helm.
Northwestern has won three of four since starting the season with losses to Western Michigan and Illinois State. The Wildcats managed only seven points against Illinois State, but that seems like a long time ago now that they've scored 38 against Iowa and 54 on the defending Big Ten champions.
''Our guys have really been grinding,'' Northwestern coach Pat Fitzgerald said. ''Earlier in the year we weren't a very good team. ... We could either pout and feel sorry for ourselves and start to point fingers, or we could just stay on the grind and keep the pedal down.''
The Spartans hadn't lost four in a row since 2006, and this was the most points they'd allowed since a 56-21 loss to Wisconsin in 2003.
Northwestern held Michigan State to 3 yards of offense in the second quarter.
''There's no easy fix,'' Dantonio said.
The Spartans made a change at quarterback for this game, starting redshirt freshman Brian Lewerke instead of Tyler O'Connor, but Michigan State's problems extend well beyond one position.
The Spartans went back to O'Connor in the third quarter, and he threw for 281 yards and three touchdowns, but Michigan State couldn't stop Northwestern (3-3, 2-1) with any consistency.
Solomon Vault returned a kickoff 95 yards for a touchdown late in the third quarter to put the Wildcats up 40-31, and the Spartans never made it closer after that.
Michigan State is off to its worst start after six games since 1994, when the Spartans were 2-4 and later forfeited away the wins.
Northwestern: The Wildcats have to be encouraged by the ease with which they shrugged off an early deficit Saturday, and although the secondary was beaten for a couple long touchdowns in the second half, Northwestern will win its share of games if it can keep creating big holes for Jackson.
''It was a good one today, but I think we're just showing what we can do,'' Thorson said. ''Passing the ball, running the ball, everything.''
Michigan State: Dantonio shook things up by starting Lewerke at quarterback, then watched his defense give up so many yards and points it didn't really matter who was throwing passes for Michigan State. The Spartans were a mess on defense and still don't block well enough on offense to put together many sustained drives.
''It's almost like everybody's at a loss for words,'' O'Connor said. ''We feel like we've been saying everything that we think we need to fix and working as hard as we can to fix it, and everybody understands that we need to get better.''
O'Connor did do his best to reclaim the quarterback spot with his work late in the game.
Lewerke had attempted only four passes this season before becoming the first Michigan State freshman to start at quarterback since Stephen Reaves in 2004. Lewerke opened the scoring with a 15-yard touchdown pass to Josiah Price in the first quarter, but the offense bogged down again in the second.
Dantonio was noncommittal about his quarterback situation afterward.
''I thought both guys obviously did some good things, and both guys obviously did some things they'd like to have back,'' Dantonio said. ''So we'll look at it and evaluate it.''
Michigan State took a 14-0 lead in the first quarter when Justin Layne scored on a 43-yard interception return. That was the last touchdown the Spartans scored for a while.
''We knew that they were going to try and knock us out early. Their backs are against the wall,'' Fitzgerald said. ''We basically got what we expected, and it was disappointing with our start, but I really loved the way our guys responded. We didn't flinch.''
Northwestern: The Wildcats host Indiana next weekend.
Michigan State: The Spartans play at Maryland on Saturday night. If you don't count games forfeited from 1994, the last time Michigan State lost five games in a row within one season was when the Spartans dropped their first five in 1991.
Follow Noah Trister at www.Twitter.com/noahtrister