The Fighting Irish have reason to feel giddy: Notre Dame emerged from the weekend ranked No. 1. Getty Images

Let's take a journey inside the exhilarated but anxious mind of a Notre Dame football fan right now. What happened Saturday in South Bend was pleasant but also a little melancholy. The Fighting Irish thumped Wake Forest 38-0, improving their record to a stunning 11-0 before their regular-season finale next weekend against rival USC. Notre Dame was good but looked to be in a jam. Despite the win, they appeared destined to stay locked at No. 3 in the BCS standings, behind shiny Oregon and Kansas State, where they'd wind up getting locked out of the national championship.

It was a thrilling, surprising Irish run. But also a tiny bit of a bummer, you know? Time was running out. The most storied college program in the sport had a real shot at going undefeated, only to get brushed aside as a third wheel. If the BCS title game didn't happen, there was talk about Notre Dame playing in the Rose Bowl against Nebraska. Also nice. But also kind of meh.

Then, in a staggering Saturday-night twist, Kansas State lost to Baylor. Then Oregon lost to Stanford.

Notre Dame, which began the evening standing on the outside, tapping against the window glass, was suddenly bursting through the front door—and a decisive No. 1 when the polls were released on Sunday.

Now Saturday's mega showdown against USC in Los Angeles is something much dreamier—a shot to qualify for the national championship on Jan. 7, a scenario some skeptics thought Notre Dame would never encounter again.

For Fighting Irish fans, this turnabout must be pretty exciting, right?

Well, sort of. This is going to be a very nervous week. I called the person I felt could best explain it.

I called Regis.

"Nervous? I am scared to death!" said Regis Philbin, Notre Dame class of 1953. It was Sunday afternoon; he had just come from church. Everything about this situation was making Regis edgy. The undefeated season. The No. 1 ranking. The national-championship chatter.

But mostly Regis was worried because underwhelming USC—a preseason No. 1—had lost Saturday to its crosstown rival UCLA. This was no good, Regis said. The Trojans were down in the gutter, with a season that could only be redeemed by crushing Notre Dame's dream Nov. 24 at the Coliseum.

This made Regis wary.

"It's a bad omen," he said.

Regis said hello to someone who recognized him as he talked on the phone. "I am walking in the street now," he explained. "People are waving."

He began speaking to these people. "Watch Notre Dame! SC is gonna be a problem, lady!"

Now let's backtrack just a moment. It is not possible for anyone to love anything more than Regis loves his Notre Dame football. And Regis, like every true Fighting Irish fan, is crazy about this 2012 team, which began the season with modest expectations—ranked 24th in the USA Today poll; not even ranked in the AP. But they'd wildly exceeded those predictions, propelled not only by a tenacious defense but also an improving young quarterback, Everett Golson, who passed for 346 yards and three touchdowns versus Wake Forest.

These Irish seem ahead of schedule. They are not a flawless outfit—that offense can be erratic, and Notre Dame nearly blew its undefeated chances in early November against Pittsburgh before winning in a third overtime. But they've won big games against teams like Oklahoma and Stanford, and under head coach Brian Kelly, they've displayed remarkable grit. The year has been a repudiation of the fashionable idea that vaunted Notre Dame couldn't compete in the 21st century.

Now, once more, it comes down to USC. At 7-4, the Trojans seem utterly beatable, especially with quarterback Matt Barkley suffering a shoulder injury on Saturday. But to Irish fans, that's the scary part. Southern Cal is now the cranky team with nothing to lose. USC coach Lane Kiffin gets to slide even more comfortably into the villain part.

Four times in Notre Dame history the Irish have lined up undefeated teams against USC and lost. And you have to understand. Regis was there in 1964 when Ara Parseghian's undefeated Irish came to the Coliseum.; Regis had an interview lined up with Parseghian at the 50 yard line for 9 a.m. the next day, win or lose (the Irish lost; Parseghian showed). Regis was there in 1970 when Joe Theismann threw for 526 yards in the rain against USC and the 9-0 Irish still fell short. The showdown gives him shivers. Even before the crazy weekend unfolded, Regis told, "the whole season is wrapped up in the USC game."

But this is a new team and a new era. Notre Dame's transformation is not complete, but it is under way. The undefeated Fighting Irish are going to USC to play for everything they want. There are already fantasy whispers of an irresistible national-title game between Notre Dame and Alabama. It is real, unexpected and a little scary.

"I am not going to sleep this week," Regis said. "I want you to know that. I know you don't care. But it's very important to me."

Write to Jason Gay at