The Spartans are known for their aggressiveness on defense, with defensive backs often left in man-to-man coverage.

Steven Branscombe

EAST LANSING, Mich. (AP) -- Before the controversial touchdown that ended Michigan State's hopes of an undefeated season, the Spartans' biggest vulnerability was already on full display.

With the ball at its own 9-yard line and 55 seconds left, Nebraska completed passes for 28 and 33 yards against Michigan State's maligned defensive backfield.

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"We all know what we need to do. Now, the rest of the season, we plan on doing it," safety Montae Nicholson said. "We plan on executing our assignments -- and get everything straight."

What has often been a strength at the back of Michigan State's defense has now become a major question after injuries to Vayante Copeland and RJ Williamson forced the Spartans to lean on less experienced players in the secondary. Michigan State started three freshman defensive backs in Saturday's 39-38 loss at Nebraska, and if the 14th-ranked Spartans are going to work their way back into the playoff picture, they're going to need to overcome problems that have been evident for a while.

"I would say we were inconsistent versus the pass on Saturday and inconsistent versus the run, as well," coach Mark Dantonio said. "It's coaching, it's playing. Everybody has to raise their level of play to get back to where we were accustomed to being. I think our players are capable of doing that, and I think our coaches are, too."

After losing cornerback Trae Waynes early to the NFL, the Spartans had to deal with two significant injuries during the first few weeks of this season. Copeland played two games before he was lost for the season because of a fractured vertebra, and Williamson played five games before having surgery on a torn bicep.

Cornerback Darian Hicks missed the last three games, but Dantonio said he passed a concussion test last week and practiced a bit.

"He's got to be able to do the things that allow him to regain that position," Dantonio said. "Got to see him tackle, got to see him play the ball in the deep part of the field, got to see him be active, explosive, because he's been sitting for a month almost."

Nebraska's Tommy Armstrong threw for 320 yards and two touchdowns Saturday. Michigan State was still in a position to win with less than a minute remaining and the Cornhuskers backed up near their own goal line. Then Armstrong found Jordan Westerkamp in a gap in coverage. On the next play, Westerkamp was open in space between two defenders for another big gain.

The Spartans are known for their aggressiveness on defense, with defensive backs often left in man-to-man coverage. The end of Saturday's game seemed to call for a softer approach that would reduce the chances of a big play -- but Nebraska gained huge chunks of yardage anyway.

"We were in our Delta package, our third-down package. We work on it each week, but it's hard when it's moving fast at the end of a game," linebacker Riley Bullough said. "Getting the signals in, putting the pieces of the puzzle together. ... Getting all those right at the same time is kind of tough, especially when you've got younger guys in there in that situation."

Arjen Colquhoun nearly came down with an interception on the next play, but he was unable to secure the ball. Then Armstrong hit Brandon Reilly for a 30-yard touchdown pass down the left sideline. Reilly went out of bounds and came back in, but the call went Nebraska's way, with officials ruling that the receiver had been forced out.

So Michigan State, which hosts Maryland this weekend, now has to win the rest of its games and hope a Big Ten title is enough to overcome the one loss in the eyes of the playoff committee. The Spartans dropped to 13th in the committee's new rankings Tuesday night, underscoring the challenge ahead of them if they want to compete for a national title.

"I sort of feel like if we win, good things happen. When you lose, negative things tend to happen," Dantonio said. "We're going to concentrate on trying to win a football game, not worry about the style points."