College football is down to its final four, as the semifinals of the inaugural 12-team playoff begin Thursday, Jan. 9. In the first matchup, Penn State will face Notre Dame for the Orange Bowl, just north of Miami.

To make it to this point, the Fighting Irish knocked out Indiana in the first round, followed by Georgia in the Sugar Bowl. They’ve done it primarily on defense, where they rank second in the country, allowing just 13 points per game. They’ve also leaned on their running game. That combination has helped them win 12 straight games.

During the Orange Bowl media day press conference on Wednesday, Jan. 8, Notre Dame head coach Marcus Freeman talked about his team’s identity.

“As you look at the course of our season, it’s been a big indication of the outcome of the game –– our ability to run the football and our ability to stop the run,” said Freeman. “It’s a mentality, it’s a mindset. Just from a defensive coaching background, when you can’t stop an offense from running the ball, it can be demoralizing.”

The other side looks much the same. Penn State beat SMU and Boise State in resounding fashion to reach the semifinal. Their defense is ranked seventh in the nation, holding opponents to just 15 points per game. In the quarterfinals against the Broncos, they held Heisman runner-up Ashton Jeanty in check, allowing him to run for just 3.5 yards a carry.

Penn State’s head coach, James Franklin, wants the same plan on Thursday.

“We look at it similar. Notre Dame does a phenomenal job with their running backs, what they average per carry, how they play up front,” Franklin said. “But now you’re also having to factor the quarterback into it, which creates another challenge, which creates more stress.”

An “x factor” that should concern Franklin –– the Fighting Irish led college football in takeaways with 31 this season. How conservative will the Nittany Lions be in their quest to protect the football? Will Notre Dame need to force a fumble or interception to win?

Thursday’s winner will face either Texas or Ohio State in the Cotton Bowl semifinal, which is scheduled for Friday night, Jan. 10, in Arlington, Texas.