EAST LANSING, Mich. (AP) - Denicos Allen picked up a fumble and ran 45 yards for an easy touchdown, glancing up at himself on a video screen along the way to make sure nobody was catching up from behind.
"He's got some pretty good wheels," Michigan State defensive coordinator Pat Narduzzi said. "Might put him at tailback."
Narduzzi was joking, but for much of Saturday's game, the Spartans' best offense was again their defense. Michigan State struggled to move the ball but remained unbeaten in Big Ten play with a 14-0 victory over Purdue.
The Spartans didn't make it past the Purdue 32-yard line until the fourth quarter, when receiver Tony Lippett threw a 5-yard touchdown pass to Andrew Gleichert on a trick play. Michigan State (6-1, 3-0 Big Ten Conference) remains atop the Legends Division but clearly has work to do with the toughest part of its schedule still to come.
"It's not a step back, not when you win," Spartans coach Mark Dantonio said. "Step back is when you lose. It's a step forward. There are plenty of people that take a step back -- that usually has an `L' beside it."
Michigan State plays at Illinois next weekend before facing Michigan and Nebraska in November.
Purdue (1-6, 0-3) kept it close after being routed by Wisconsin and Nebraska in its first two conference games, but Paul Griggs missed two field goals.
The Spartans entered with the nation's top-ranked defense, and Allen opened the scoring in the second quarter with Michigan State's fifth defensive touchdown of the season. Max Bullough hit quarterback Danny Etling, the ball popped free, and Allen scooped it up and scored easily.
"I saw myself on the screen -- I kind of glanced up to see if anybody was behind me, because I didn't want to look back," Allen said. "I saw there was a lot of space behind me."
Purdue converted a fourth down thanks to a penalty, which gave the Boilermakers the ball at the Michigan State 34 with 9 seconds left in the second quarter. That was as far into opposing territory as either team advanced the ball in the first half, but Griggs was short on a 51-yard field goal attempt.
"I think we're making strides but obviously we're not making enough plays to get the ball into the end zone," Purdue coach Darrell Hazell said. "We haven't been able to finish drives all season long and that was the case again today."
The Boilermakers lost to Wisconsin and Nebraska by a combined 85-17, but Michigan State couldn't put Purdue away until late. Griggs came up short again from 41 yards in the third quarter, and the Spartans added an insurance touchdown in the fourth. Connor Cook completed a pass to Macgarrett Kings for 25 yards on third-and-12, and a 26-yard catch-and-run by Josiah Price put the ball at the Purdue 7.
Two plays later, Lippett took the ball on what looked at first like an end-around, but he threw to an open Gleichert for a touchdown.
Dantonio said he'd considered a quarterback change but was pleased with the way the offense performed on its last couple drives.
Cook went 13 of 25 for 107 yards, although at one point he had only 17 yards on eight completions.
"It's all on me," Cook said. "But we could have given in, made stupid decisions and turned the ball over. We didn't."
Etling was 14 of 25 for 160 yards, but he also threw a crucial interception in the end zone in the first quarter, after Purdue had reached the Michigan State 37 with a fourth-down conversion.
Jeremy Langford had 131 yards on 24 carries for Michigan State, which became bowl eligible with the win. Last year, the Spartans didn't secure a bowl berth until the final game of the regular season.
Punter Mike Sadler gave the Spartans a lift, landing three punts inside the 10-yard line, but this was an uninspiring offensive performance from Michigan State. The Spartans scored 42 points the previous weekend in a win over Indiana, but that progress seemed to come to a halt against Purdue.
"We talked all week about not being satisfied with a couple good weeks," co-offensive coordinator Dave Warner said. "We talked about taking it to the next level, taking a step forward, and we didn't do that today."
Of course, with this defense, Michigan State doesn't always need to score much.
"We come out and play defense, and that's our job. We expect to stop them every down," Narduzzi said. "At halftime I said, `Hey, they ain't scoring. We're going to get a shutout.' That was kind of part of the halftime speech."