At 6-foot-1, 210 pounds, Nebraska's Demorrio Williams is smaller than some of the tailbacks he regularly takes down.

Try pouring him into the typical linebacker mold, however and it quickly becomes a futile attempt. Williams isn't a typical linebacker and, most likely, never will be.

Yet, for all the things he isn't -- big, experienced -- he is a constant threat to make a big play and an even bigger headache for opposing coaches trying to draw up a game plan.

Ask Utah State quarterback Travis Cox, who experienced first-hand the speed and agility Williams brings as a rush end on third downs. Nebraska's No. 7 seemed to perpetually find Cox and dragged him down three times -- tying the Cornhuskers single-game record for sacks by a linebacker and winning Big 12 Player of the Week honors for his efforts.

Those records are nice, Williams says, but they're not the biggest honors bestowed on a Nebraska football player. That distinction would go to the black practice jersey worn by the 11 starting members of the 'Huskers defense, perhaps the most famous practice uniform in college football.

And Williams, who spent two years at Kilgore, Texas, junior college before transferring to Lincoln, has made it a habit of donning the duds since arriving on campus.

As a junior last season, his first with Nebraska, Williams led the team in tackles with 92 stops, including a career-high 13 in the 'Huskers' regular-season final against Colorado.

Having that presence at linebacker was an enormous boost for first-year defensive coordinator Bo Pelini when he arrived from the Green Bay Packers. It wasn't, however, making full use of Williams' potential.

That problem has been largely corrected by moving the ultra-speedy Williams, who played free safety in high school, to the defensive line on passing downs. While opposing linemen often outweigh him by almost 100 pounds, Williams' fast first step is too much for the tackles to take.

"He presents some problems [for opponents]," Nebraska defensive coordinator Bo Pelini said. "He's an unusual athlete to be out there. They're used to seeing bigger guys without as much burst."

While the Penn State Nittany Lions are used to seeing fast pass rushers after squaring off against Boston College defensive end Mathias Kiwanuka last weekend, they haven't done well against them. Kiwanuka spent almost as much time in the Penn State backfield as Lions' tailback Austin Scott did last weekend.

With better acceleration than the 6-foot-8, 246-pound Kiwanuka, Williams instantly presents match-up problems for the Lions this weekend.

Penn State football coach Joe Paterno has mentioned screens and draws as a way to slow down an aggressive 'Husker defense, but it didn't work well against the Eagles last weekend. Compounding the problem is the inexperienced personnel in the Penn State backfield that has made an adventure out of pass protection this season.

When asked about what kind of weekend he'll have, Williams was quick to downplay the hype.

"Week in and week out I try to just go at them," Williams said. "It's real hard because you play one week hard and you have a great game and then the next week you never know what to expect."

Fans and coaches are equally uncertain about how to approach Williams. He's many things to the Nebraska defense, but typical isn't one of them.