Tasked with replacing seven starters from last season, No. 3 Ohio State expected to be challenged on defense heading into 2020.

After allowing a touchdown on the very first drive in which in had to defend this season, the Buckeyes defense buckled down and didn't allow another touchdown score for four consecutive quarters.

No. 18 Penn State scored just 10 points in the first three quarters of Saturday's contest and just three touchdowns total as Ohio State's defense buttoned up some areas of its game while others may need addressed.

We take a look at each unit of the Buckeyes defense and compare them to that of all of college football, with a C grade representing average.

Defensive line

After allowing 210 rushing yards in the season-opener, the Nittany Lions' running game was shut down on Saturday.

Penn State's Devyn Ford and Sean Clifford combined for 42 rushing yards early as the absence of Journey Brown and Noah Cain loomed large, and the Nittany Lions produced four, a loss of nine and positive-seven yards on the ground in each quarter thereafter.

"In order to be a great defense, you have to stop the run," defensive end Jonathon Cooper said. "If you let the offense run on you all day then you're not a very good defense. That's a huge emphasis for us, stopping the run."

Zach Harrison (DE), Antwuan Jackson (DT), Tyreke Smith (DE) and Tommy Togiai (DT) were the four starters up front with Cooper, Tyler Friday, Haskell Garrett and Javontae Jean-Baptiste all checking in as the game progressed.

Togiai led the Buckeyes in tackles with seven, and also recorded three sacks along his eye-popping stat sheet. Cooper and Harrison also had 0.5 sack, while Jean-Baptiste had one sack of his own.

Grade: A+

Linebackers

As the defensive line was busy up front, the linebackers added extra pressure and patrolled areas in open field to account for the Nittany Lions' passing attack.

In the first quarter, Penn State gathered just 29 yards through the air and converted one first down by way of a throw. Not much else came the following quarter as the Nittany Lions had possession for just four minutes of that frame, and suppressed Clifford to just 29 passing yards in the half.

"When it comes to a fight or a football game, you're going to get punches thrown right back at you," Cooper said. "We wanted to make sure we got out on them early."

The Buckeyes defense anticipated return punches, and they got them immediately out of the half.

Clifford went 5-5 on the first drive of the third quarter, each for more than 11 yards. None of the linebackers collected a tackle on that drive which seemed to throw the momentum the way of Penn State.

Tuf Borland, Baron Browning and Pete Werner earned starts at each linebacker position and combined for 11 tackles, while Dallas Gant and Craig Young checked in at times.

Browning had a questionable roughing-the-passer penalty in the first quarter that allowed Penn State to wiggle out of a three-and-out and ended up scoring three points on a field goal. But Browning also had an impressive pass defended when he went toe-to-toe with tight end Pat Freiermuth on that same drive with 3:39 left.

Grade: A-

Secondary

Similarly to the linebackers unit, the Ohio State secondary limited Penn State in the first half.

Sevyn Banks (CB), Marcus Hooker (S), Wade (CB) and Marcus Williamson (CB) started in the secondary, and Josh Proctor saw game time as well.

The secondary began the game very strong, but the Nittany Lions took advantage of some weak spots that resulted in points later in the game.

"That's just all up to the film. Things are going to happen, plays are going to happen," Cooper said. "They're a really good team, we knew that coming in. We knew they weren't going to lay down in the second half."

The Nittany Lions converted five passing first downs in the third quarter and had 100 receiving yards, including a 14-yarder to Jahan Dotson who was noted by Shaun Wade as a "very quick, deep ball threat" earlier in the week.

Dotson wasn't finished. He made two impressive catches on a drive at the start of the fourth quarter and both went for more than 21 yards, including a one-handed touchdown grab. The junior wideout later hauled in his third touchdown reception and finished the game with 144 yards receiving on eight total catches.

Penn State out-threw Ohio State 152-69 in the fourth quarter, and the Nittany Lions finished with 281 passing yards as five receivers caught a pass and three of whom totaled more than 46 receiving yards.

Despite Ohio State having control throughout the game, the contest had a feel that Penn State was within striking distance. Hooker cinched that feeling when he snagged his first interception as a Buckeye with 3:35 to go in the fourth quarter, icing the game.

"We got that big turnover late, Marcus was opportunistic on that play," head coach Ryan Day said.

Grade: B-

Overall

The Buckeyes defense wasn't on the field too long during the game as the time of possession weighed drastically in favor of Ohio State, 37:01 to 22:59.

Ohio State also limited the Nittany Lions to a 33% third-down conversion percentage.

Penn State still converted 20 first downs and scored 25 points, which are the third-most allowed by Ohio State to the Nittany Lions since 2001.

At the end of the day, Day and the Buckeyes took care of business and showed that the defense could hold its own against a ranked program and in enemy territory.

"A gutsy win on the road. Hard to win here, proud of our guys."

Grade: A-