Justin Jackson rushed for 188 yards and two touchdowns, and Northwestern 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.
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.
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: After starting the season with losses to Western Michigan and Illinois State, the Wildcats have rebounded to win three of four. Northwestern has to be encouraged by the ease with which it shrugged off an early deficit Saturday, and although the secondary was beat for a couple long touchdowns in the second half, the Wildcats will win their share of games if they keep creating big holes for Jackson.
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.
O'Connor did do his best to reclaim the quarterback spot with his work late in the game.
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.