LINCOLN, Neb. -- Nebraska defensive coordinator Carl Pelini believes bigger is better in the secondary against seventh-ranked Wisconsin.
The No. 8 Cornhuskers made changes at three of the four positions last week, hoping it will help shut down the Badgers' receivers Saturday night.
Those targets include 6-foot-3, 220-pound star Nick Toon, who matched his career high with seven catches for a career-best 155 yards and two touchdowns against South Dakota last week.
"These coaches aren't scared to switch it up," Huskers free safety Austin Cassidy said. "If something's not working, or something's not working as well as they want it to, they're going to be willing to switch it up at any time."
And they did.
Corey Cooper is Nebraska's new right cornerback, a position he has never played. At 6-foot-1, 210 pounds, he is an inch taller and 20 pounds heavier than the guy he replaced, Andrew Green.
At left cornerback, 5-foot-10, 205-pound Alfonzo Dennard, who missed the first three games because of injury, replaced 5-foot-11, 185-pound Ciante Evans, a move that was expected.
Daimion Stafford, at 6-foot-1, 210 pounds, started last week's game at nickelback for the first time. His spot at strong safety was filled by the 6-foot-2, 210-pound P.J. Smith.
The Huskers were 80th in pass efficiency defense after the first three games, giving up 233 yards a game and six touchdown passes. Green was beaten repeatedly, and Evans played extremely soft coverage.
Pelini wants his defensive backs to challenge receivers.
"You put Dennard and Coop and Daimion out there together, that's a pretty physical defensive backfield," he said. "That's what we lack at times is aggression -- getting on bodies and getting hands on people."
Cooper, a redshirt freshman, appeared on special teams and as a backup safety in the first three games. His coaches like his size and speed, thought he could be a sound cover man, and moved him to cornerback on Sept. 19.
His initiation in the 38-14 win at Wyoming didn't go smoothly. He had trouble handling the 7,220-foot elevation and got sick to his stomach in the first quarter. He gave up a 48-yard touchdown to Mazi Ogbonna, who beat him on a slant in the second quarter.
"I just wanted to play a perfect game," Cooper said. "I know it's not possible. I just wanted to make the coaches right by putting me out there."
Wisconsin's balanced offense presents a huge challenge.
Russell Wilson is second nationally in pass efficiency and is an explosive runner.
"Any time you have a great running game, if you have a quarterback who is as good as he is, they force you to defend the run and put a lot of pressure on your defensive backs," Pelini said. "You need them in run support but at the same time they have to be disciplined in their keys and cover their guys."
Cassidy said the Nebraska defensive backs won't be intimidated after facing receivers such as Justin Blackmon of Oklahoma State and Ryan Broyles of Oklahoma last year. They beat the Cowboys and lost to the Sooners.
"It helps in the secondary because we know what we're capable of," Cassidy said. "That doesn't mean we're going to go out there and shut people down every single play. ... Playing defensive back, you can't be scared or intimidated to go against someone because that's just a recipe for disaster."