They meet in South Bend with egg on their faces, two historic programs with their seasons trending downward, despite being in very different spots. Two teams with championship aspirations, with more questions than answers midway through the season.

USC is undefeated but somehow falling in the rankings, from preseason No. 6 to No. 10. That tends to happen when a preseason College Football Playoff contender chooses to play without a defense.

Notre Dame is 5-2 and coming off a rather embarrassing 33-20 loss at Louisville, 2 weeks after an only slightly embarrassing 17-14 home loss to Ohio State, punctuated by a Buckeyes 1-yard touchdown run with 1 second left with the Fighting Irish playing with only 10 players on defense for the final play.

So, we’ve got one team with no defense and another team with an incomplete defense.

Forget South Bend. Call it South Break. Because one of these teams is about to fracture into a million pieces.

*****

It says a lot about Lincoln Riley’s undefeated Trojans that they venture east to play a 2-loss Notre Dame team as 2.5-point underdogs. The national perception of the Trojans has tanked in recent weeks, courtesy of an uninspiring run that has even the most loyal Alex Grinch supporters ready to tear their eyes out.

USC is undefeated, but you wouldn’t know it by the chatter. Three weeks ago, coming off an early bye week that was supposed to be all about taking things to the next level, the Trojans allowed 28 points to an anemic Arizona State offense and led by just 35-28 midway through the 4th quarter before adding another touchdown for padding. The following week in Boulder, USC built a 34-7 lead before a 2nd-half onslaught from the Buffaloes, eventually outlasting Colorado, 48-41.

Then on Saturday, redshirt freshman quarterback Noah Fifita, making just his second career start, tossed 5 touchdown passes as Arizona built an early 17-0 lead, only for USC to come out on top 43-41, in triple overtime.

“Our team’s fight and resolve to get back and find a way to win that, with some of the craziness that happened in this game, I’m really proud,” Riley said. “A lot of teams don’t win this game. You go down 17-0 and you don’t recover.”

That’s were we’re at with the Trojans. Riley offering up platitudes and celebrating a top-10 team’s resolve after needing triple overtime … to beat an unranked team … with a backup quarterback … at home.

We’re long past the point of Riley holding his coaches or players responsible for USC’s persistent malaise.

But to watch him try to spin a win like that over the likes of Arizona? Embarrassing.

Then, if adding insult to injury, Riley actually credited a defense that allowed 41 points at home.

“I thought we took some great steps,” Riley said, absurdly. “Again, when you go down 17-0, you get tested right there internally. Do you really believe? Are guys ready to really fight? As Jamil (Muhammad) said and I’ve said before, your culture gets tested quick, and the defense is what got us going. Defense is what won this football game. It got us going in the beginning down 17-0 and closed it against a play that they’ve been running well all night.

“Closed it with a huge TFL to win the game, so I’m proud of those guys.”

Defense is what won the Trojans the game?

In a game they gave up 41 points?

In a game Caleb Williams scored another 4 touchdowns?

Utterly absurd.

******

On the other side, you’ve got a Fighting Irish squad reeling from the end of a record 30-game regular-season ACC winning streak.

This wasn’t a 3-point loss at the last minute to the Buckeyes, one of a handful of legitimate CFP favorites.

This was a sound thrashing from a good-but-not-great Louisville team, a full-on harassment of star quarterback Sam Hartman, who entered the game with 14 touchdowns and zero interceptions. Against the Cardinals, Hartman was picked 3 times, including the first drive of the game.

He was also sacked 5 times, and the Irish managed just 44 total rushing yards.

“Everybody is going to point the finger at Sam,” Freeman said. “You better point the finger at me. We have to do a better job of protecting our quarterback and putting him in situations to have a higher percentage for success.”

It was Hartman’s 2nd straight loss to Louisville as a top-10 team. Last year, Hartman’s 10th-ranked Wake Forest squad fell to the Cardinals, 48-21. The Demon Deacons then lost 3 straight.

Notre Dame is in danger of the same thing happening this year.

“You don’t have much time to feel sorry for yourself,” Freeman said. “I’m going to really count on our leaders to make sure our guys understand we have to learn from this game and then we have to move forward and get ready for USC. We cannot sit here and mope and feel bad for ourselves. We have to move forward. This will be a true test of our leadership.”

*****

All that is do say: The stakes are huge in South Bend.

You’ve got one team with a defense that has been pushed to the test time and time again.

Will the Trojans’ bendable defense finally break?

Can the Irish get their offense on track?

For a pair of top 15 teams with championship aspirations, midway through the year, they sure have more questions than answers