The No. 3 Ohio State Buckeyes passed their second big test of the season on Saturday with a 20-12 victory over No. 7 Penn State.

The Buckeyes rode their defense and a stellar performance from wide receiver Marvin Harrison Jr. to stay perfect at 7-0 this season.

After the game, head coach Ryan Day was sure to praise Harrison Jr. at the first chance he got.

Ryan Day on Marvin Harrison Jr. vs. Penn State

"I just think the standard he has set here, his work ethic and what he means to Ohio State; It's about leaving a legacy behind," Day said during his postgame interview. "We're only halfway through the season so I'm not going there yet but he's on his way, I'm proud of him."

Back in the press room, Day continued to hype up his top offensive weapon.

"It's hard for me to find somebody who's better in the country," Day said.

However, he wasn't under the illusion that the Ohio State offense played well as a whole.

Ryan Day on the Ohio State offense vs. Penn State

"I know we left a lot of plays on the field today on offense," Day said while pointing out that the performance was relative to Penn State's top-rated defense.

The head coach's decision to go for it on fourth-and-two from the goal line was a potential game-changer as the Buckeyes failed to convert and Penn State's offense got the ball back down just four.

Day explained that he was comfortable with the defense being able to stop Penn State from going 98 yards to score. But he also wanted more from the offense.

"We've got to get in from the two-yard line, there's no excuse for that. That's our expectation," Day said.

In the end, the Ohio State offense led by Kyle McCord was good enough to win, but there are things he wants cleaned up.

"The most encouraging thing, we come out of this game feeling like we should have won the game by a few touchdowns at least," Day said.

Ryan Day on Ohio State's crowd

The head coach felt the Buckeye faithful at the Horseshoe lifted the level of his team.

"I thought first off the crowd was tremendous...When the 'Shoe is rocking like that it's a difference maker," Day said.

The crowd's response to JT Tuimoloau's sack to start the fourth quarter was as loud as Day has heard Ohio Stadium get.

Ryan Day on Ohio State's defense vs. Penn State

When it comes down to it, the Buckeyes won because their defense grabbed the game by the scruff of the neck. They stopped the run, they forced Penn State to throw the ball when they didn't want to and they got the stops they needed.

Day credited defensive coordinator Jim Knowles with an excellent game plan and execution.

The key stat of the outing was the Buckeyes holding Penn State to 1-of-16 on third downs.

"Unbelievable job," Day said. " I think that was a combination of the rush and the coverage.

He specifically hailed cornerback Jermaine Mathews Jr. for stepping up with Denzel Burke missing the game.

"If we can play like this, that's championship-level defense."