Northwestern isn't expecting things to go as smoothly as they did last year against Penn State. Facing the best pass rush in the country is big reason why.

The Wildcats, at No. 21 in the season's first College Football Playoff rankings, emerge from their bye looking for another balanced performance in order to beat the Nittany Lions again Saturday.

Northwestern (6-2, 2-2 Big Ten) never trailed in a 29-6 victory over Penn State in its conference opener last season, holding the Nittany Lions to 266 yards of offense.

Coach Pat Fitzgerald, though, feels there was some luck involved for his Wildcats.

"I think we were very fortunate," Fitzgerald said. "We were able to get some pass rushes and they missed a couple plays they had us on."

While Penn State had only one sack that day to Northwestern's four, this year's Nittany Lions (7-2, 4-1) have regularly wreaked havoc on opposing quarterbacks. The defense leads the nation with 36 sacks - four more than it had all of last year - and ranks fourth among FBS teams in pass defense at 157.9 yards per game.

The secret to the Nittany Lions' success is in their rotation, using their depth on the line to keep the starters fresh and the backups active. That's shown in Penn State's 22 second-half sacks, including 16 in the fourth quarter.

"That's kind of who we are," coach James Franklin said. "We wear people down with our pass rush."

As the Nittany Lions dominated in every facet in last weekend's 39-0 win over Illinois, the defense yielded a season-low 167 yards and had four sacks. Carl Nassib got one of them to push his FBS-leading total to 14 1/2.

"It's a nightmare," Fitzgerald said. "First of all, they're playing multiple guys. The whole group is fundamentally very good and very, very active. They're relentless in their effort.

"They're playing a lot of guys. They're talented. They're deep. They're fast. They're physical. They're tough. They do a lot of things very, very well. They have athletic guys who can rush the passer."

Northwestern, though, has let Clayton Thorson get sacked only 11 times. Some of that can be credited to the freshman's ability to escape the rush, having run for 297 yards and 4.6 per carry with five touchdowns.

His legs were vital to a 30-28 win at Nebraska on Oct. 24 after he was held to six yards on 14 carries in losses to ranked Big Ten foes Michigan and Iowa. Thorson had 126 of the team's 156 rushing yards versus the Cornhuskers, also throwing for 177 and totaling two TDs.

"We'd like to have as much balance as we possibly can," Fitzgerald said. "That's something that's going to be a great challenge against this defense. We've got to find ways to move the ball."

Getting Justin Jackson going again could help since Penn State allows an average of 143.9 rushing yards - 235.0 in three road games. The sophomore running back has only gained 95 yards on 36 carries over the last three games after rushing for 636 in the previous five.

"Our offensive line needs to show up and have the best game they've had all year," tight end Dan Vitale said.

Northwestern's pass defense is looking to bounce back from giving up a season-high 291 passing yards to the Cornhuskers. The unit yielded an average of 146.7 through the first seven games. Nebraska's Tommy Armstrong became just the second quarterback to throw a touchdown pass against the Wildcats.

They pose another stiff test for Christian Hackenberg, who completed 22 of 45 passes for 216 yards with one pick against Northwestern last year.

The junior hasn't tossed an INT in six straight games, throwing for 1,415 yards with 12 scoring passes. He's coming off his most efficient performance of the season, hitting 21 of 29 passes for 266 yards and two scores while catching a 14-yard TD from running back Nick Scott.

"We're going to have to be balanced," Franklin said. "Be able to run the ball. Be able to mix in the high-percentage throws and then find situations where we're able to take some shots and create some explosive plays."