Notre Dame players give coach Brian Kelly a Gatorade shower after the Irish defeated USC to earn a spot in the BCS Championship Game. (AP)

Three short months ago, one dynasty was ranked No. 1 and one was unranked, an afterthought on the national scale.

On Saturday night, two pictures told the story about what has happened since then.

Picture No. 1: USC quarterback Matt Barkley, frowning, arm in a sling, on the Trojans' sideline watching.

Picture No. 2: Notre Dame coach Brian Kelly and his star pupil, LB Manti Te'o, embrace each other after a perfect season.

Notre Dame’s Theo Riddick ran for a career-high 146 yards and a touchdown in the victory over USC. (US Presswire)

Irish eyes were smiling from South Los Angeles to South Bend and now all the way to South Florida, as Notre Dame advanced to the national championship game with a 22-13 win over the Trojans on Saturday night at the Los Angeles Coliseum.

The Fighting Irish (12-0) became the first preseason unranked team to advance to the title game, and they did it in the style that has become their hallmark under Kelly: Gritty defense and stalwart play against opposing stars.

"Well, that's who we are," Kelly said. "It's been our defense all year. Our offense is able to manage enough points."

Notre Dame limited the potent USC attack to 281 total yards -- made less potent with the injury to Barkley, suffered last Saturday at UCLA, and the arrival of little-used backup Max Wittek. Wittek had just 186 passing yards, including a combined 167 yards and a score for USC star receivers Marqise Lee and Robert Woods. With Woods and Lee bottled up, Wittek could hardly look elsewhere, as he completed just two other passes, one for 10 yards to Soma Vainuku and one for 9 to Xavier Grimble.

USC (7-5, 6-3) had 19 first downs and five drives that covered fewer than eight yards each, as Wittek (14 for 23) threw interceptions to close the first half and open the second.

Perhaps more damaging to the Trojans' cause: Three drives of more than 54 yards resulted in two field goals.

“We weren’t able to finish a few drives and that was very telling,” USC coach Lane Kiffin said.

Notre Dame wasn’t able to finish much, either.

Kyle Brindza wasn't complaining.

Brindza had five field goals, including a 52-yarder with one second left before halftime to put Notre Dame up 16-10.

Theo Riddick had 146 yards and a score on 20 carries and Everett Golson was 15 of 26 for 217 yards for the Fighting Irish, who will have to wait a week to discover their title game opponents.

They're willing to play the waiting game, considering where they started.

And what they finished: USC's nightmare regular season.

(For more on the game, check out CBSSports.com's Eye on College Football blog)

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