Top-ranked USC's potential prize is tangible.
The Trojans are 11-0 overall, 7-0 in conference play and will arrive at the sold-out Rose Bowl with a chance to advance to their first bowl championship series title game.
USC, which claimed a share of the national championship last season, has won five consecutive games against UCLA. If the Trojans extend their streak -- the longest by USC in a series that dates to 1929 -- they are expected to maintain their spot atop the BCS standings and earn a berth in the Orange Bowl on Jan. 4.
"We're sitting where we want to be sitting and we realize what we have to do to get where we want to go," USC quarterback Matt Leinart said.
Trojan defensive lineman Shaun Cody acknowledged what Coach Pete Carroll has steadfastly refused to discuss with his players.
"There is so much riding on this game, as far as going to the big dance," Cody said.
UCLA's potential payoff is more difficult to quantify, but no less dramatic.
"They have everything to lose and we have everything to gain," UCLA flanker Tab Perry said. "It's a perfect day for an upset.... This is pretty much a national championship game for them. They beat us, they get to go. They lose and everything is different."
Perry was referring to perception.
UCLA is 6-4 overall and 4-3 in conference play. A victory over USC would move the Bruins from the Insight Bowl to the Sun Bowl. More important, it could thunderously help UCLA make up some of the huge distance that has grown between the programs during Carroll's four seasons.
"This would be huge for recruiting," Perry said. "Right now, everyone is on the USC bandwagon. But if we could go out and show that we could beat them, that would let people know.... It would just do wonders for our program."
UCLA is playing for the first time since defeating Oregon, 34-26, on Nov. 13. The three-week break allowed the Bruins to mend injuries and prepare, but it also might have slowed the momentum they had after they'd won at Autzen Stadium in Eugene.
"This is the best team in the country," UCLA Coach Karl Dorrell said. "We are going to have to raise the bar and raise our level of play ... in order to have an opportunity to win this football game."
USC is coming off last week's 41-10 victory over Notre Dame, a game in which Leinart cemented his status as a Heisman Trophy front-runner by passing for 400 yards and five touchdowns.
LenDale White is the Trojans' top rusher for an offense that also features running back Reggie Bush, the nation's most dangerous multipurpose threat. Sophomore flanker Steve Smith, freshman split end Dwayne Jarrett and junior tight end Dominique Byrd are top receivers, as is Bush.
UCLA ranks 105th out of 117 teams nationally in total defense. The Bruins surrender 431 yards and 25.6 points a game.
"The issue will be the skill," Dorrell said. "We are going to have to match up with their skill and try to contain the big plays they make offensively."
With sophomore Maurice Drew limited because of an ankle injury, senior Manuel White and freshman Chris Markey are expected to lead a UCLA rushing attack that ranks 18th nationally, averaging 208 yards a game. Split end Junior Taylor, tight end Marcedes Lewis and flankers Craig Bragg and Perry are the top targets for quarterback Drew Olson, who has passed for 18 touchdowns, with 11 interceptions.
USC is fifth nationally in total defense, surrendering 269 yards a game. The Trojans are second in rushing and scoring defense and third in pass-efficiency defense.
Cody, a Lombardi Award finalist, expects the Bruins to offer a few surprises, especially after three weeks of preparation.
"Three weeks is like a bowl game," he said.
"They definitely have some tricks up their sleeves and some new stuff to show us. We just have to make adjustments and find out what they're trying to do. It's been happening to us all year."
USC routed the Bruins at the Rose Bowl in 2002, 52-21, and ran the victory into an Orange Bowl appearance against Iowa.
Last year, the Trojans beat UCLA, 47-22, then defeated Oregon State in the regular-season finale and finished No. 1 in both major polls. USC, however, finished third in the BCS standings and was denied a chance to play in the BCS title game.
As his team made final preparations for UCLA, Carroll said he would ponder possible BCS ramifications after the game.
"Sometime Sunday or [tonight], we'll figure out what it all means," he said. "But right now, it's just about this game and getting it done."
(BEGIN TEXT OF INFOBOX)
Today's big games. All times PST:
No. 1 USC (11-0)
vs. UCLA (6-4)
Pac-10 finale, 1:30 p.m., Ch. 7
* Is there any way Trojans could get squeezed out of the Orange Bowl?
No. 4 California (9-1)
vs. Southern Mississippi (6-4)
Postponed makeup, 4:45 p.m., ESPN
* Bears have to hope UCLA's 1998 hurricane history doesn't repeat.
No. 2 Oklahoma (11-0)
vs. Colorado (7-4)
Big 12, 5 p.m., Ch. 7
* Sooners backed into title game last year. They have to win this time.
No. 3 Auburn (11-0)
vs. No. 15 Tennessee (9-2)
Southeastern, 3 p.m., Ch. 2
* When it comes to the BCS and unbeaten teams, three's a crowd.
No. 9 Miami (8-2)
vs. No. 10 Virginia Tech (9-2)
ACC finale, 10 a.m., Ch. 7
* Two USC foes in other BCS games? That sounds a little Hokie.
vs. South Florida (4-6)
Regular-season finale, 8 a.m., ESPN2
* Panthers should get BCS berth with a win, but this is the BCS.
vs. Navy (8-2)
11:30 a.m., Ch. 2
* Everyone supports the men in uniform in this traditional matchup.
Times staff writer Lonnie White contributed to this report.