CHAMPAIGN, Ill. — The prosperous stretch extended into the third quarter against Illinois and demonstrated how Penn State has enhanced its defense during the 28 days between the team’s first and fifth games.

The key particular: the Nittany Lions thwarted the Fighting Illini’s first nine third-down attempts.

For a unit facing numerous questions after faltering against Ohio University on Sept. 1, a fast start to Big Ten play offers a jolt.

Penn State stymied Illinois 35-7 behind a defense that didn’t prolong series. The Nittany Lions forced five three-and-outs. Another Illinois possession lasted four plays because Penn State accepted a 10-yard holding penalty. The Fighting Illini didn’t successfully convert a third down until midway through the third quarter.

“That’s a sign of good defense when you make three-and-outs,” sophomore defensive back Adrian Amos said. “That gives you a break on and off the field. It seemed like we didn’t have too many plays. We got on a roll on third down and were getting off the field so we could recover.”

Penn State (3-2) ran 82 offensive plays, 13 more than Illinois. Only two Fighting Illini drives consumed more than three minutes.

Illinois’ first extended drive, which lasted 14 plays and traveled 74 yards, ended with linebacker Michael Mauti intercepting a Nate Scheelhaase pass at the goal line and returning it a school-record 99 yards to the Fighting Illini 1-yard line. The interception marked the final offensive snap of the first half.

The game then ended with Illinois mustering a 15-play, 87-yard drive that consumed 6:07 and yielded no points. A four-touchdown lead allowed Penn State to use many defensive reserves on that drive.

“That last drive felt like it took about 25 minutes,” defensive coordinator Ted Roof said.

Still, it felt better than the second half against Ohio University when Penn State allowed 21 points and 301 yards.

Going 11-for-12 on third down in the half helped the Bobcats leave Beaver Stadium with a 24-14 victory.

The defense has tightened since the loss, surrendering just 44 points in the past four games. The unit is forcing close to three turnovers and allowing just 11 points per game since the opener.

“Guys have been playing lights out,” senior outside linebacker Gerald Hodges said. “We enjoy playing, we enjoy being out there, we enjoy each other, being revved up and ready to play each and every game.”

The vibrant play started early against Illinois, with Mauti forcing a fumble on a punt return. The turnover allowed Penn State to run the game’s first 11 offensive plays. The Nittany Lions led 7-0 when the defense played its first series, a four-play drive that started with Hodges and Glenn Carson blowing up a screen pass.

Roof said third-down and red-zone play are among his unit’s biggest improvement since the opener. But, Saturday’s matchup with undefeated Northwestern (5-0) at Beaver Stadium has Roof guarded about what awaits.

“We can get a lot better,” he said. “We have to get a lot better to get to where we want to be. That’s the goal every week. Certainly we will put on the tape and there will be a lot of things that we would have liked to have done better. We have to keep working to get better. I think that has happened each week.”

The improvement has generated national attention for the unit. Mauti earned the Walter Camp Defensive Player of the Week Award for his play against Illinois. He’s a strong candidate to add his second Big Ten Defensive Player of the Week Award when the conference announces its weekly honors today.

The Nittany Lions are among the national leaders in two major categories. They are tied for 14th in scoring defense (13.6 points per game) and turnover margin (1.4).

“To me, they’re a good defense,” coach Bill O’Brien said. “They’re coached well. They understand the schemes. They play well as a unit. They communicate really well. They tackle well for the most part. They’re making plays on the ball a little better than we were early in the year. They’re doing a decent job on third down. They’re getting better every week, like our football team.”

Follow Guy Cipriano on Twitter @cdtguy.