LOS ANGELES — Stanford's Andrew Luck will finish just ahead of Southern California's Matt Barkley in just about every football metric that counts if both quarterbacks head to the NFL next year. The Pac-12 standings, head-to-head victories, Heisman Trophy voting, pro draft boards — Barkley realizes he'll probably always be looking up at Luck.

Barkley won't feel second-best if his 20th-ranked Trojans can figure out some way Saturday night to stop the juggernaut that's been built around his Northern California counterpart.

Two of the nation's top quarterbacks face each other for the third time in their college careers when No. 4 Stanford (7-0, 5-0 Pac-12) looks to extend its 15-game winning streak with a third straight victory at the Coliseum over USC (6-1, 3-1).

Luck and Barkley have only a passing acquaintance, seeing each other a few times off the gridiron at media events, so there's hardly a personal rivalry. What's personal to Barkley is the feeling he gets when he thinks about Stanford's two victories over the Trojans during his tenure — the first in a historic blowout in 2009, the second on a field goal as time expired last season.

"I don't like the thought of losing or being embarrassed like that in my head," Barkley said. "I guess it's kind of a pride thing, wanting to prepare so well that that doesn't happen, so I don't have to go through that, don't have to face a loss like that."

Luck left last season's victory over USC with more relief than excitement after engineering a last-minute drive to the decisive field goal. That victory was the start of Stanford's current winning streak, and the Cardinal haven't even been in a tight spot since last November, winning a record 10 straight games by at least 25 points.

"He's a great guy, great football player," Luck said of Barkley. "It's fun to watch him play. I really do enjoy watching him play on TV. Except for this week, obviously."

The role reversal in USC's oldest rivalry between the Pac-12's two private California schools still seems strange to the Trojans fans who are expected to sell out the Coliseum for this meeting. In fact, anybody looking to track Stanford's rise as an improbable college football power can find major landmarks in the Cardinal's victories in the last two trips to USC's historic home.

In a night game in 2007, coach Jim Harbaugh's Cardinal recorded one of the most improbable upsets in recent history, snapping the No. 2 Trojans' conference-record 35-game winning streak with a one-point victory as a 41-point underdog. Two years ago, Stanford returned for the highest-scoring performance ever against USC, cementing its rivalry reversal with a 55-21 thrashing.

"That doesn't sit well with anybody who cares about this program, but that's a great team they've built up," USC linebacker Chris Galippo said. "We can't do anything about the past. We just have to try to get it back to the way it was."

In a measure of just how completely this rivalry has shifted in only two years, USC might even be proud if it's only able to end Stanford's streak of 25-point-plus victories — the longest such stretch by any school since at least the 1930s.

USC's dynasty might be dead, but the Trojans are quietly thriving in their new role as undermanned underdogs while navigating a half-decade of NCAA sanctions. After several unimpressive wins this season, they looked sharp in a 14-point victory at Notre Dame last week, capping a three-game winning streak.

While USC assistant head coach Monte Kiffin spent this week working on ways to pressure Luck, Stanford coach David Shaw's staff has been worried about a Trojans offense rounding into potent form.

"They've run the ball better, (and) the quarterback has been playing at a high level all year," Shaw said. "Robert Woods is about the best route-running receiver I've seen in college football in about 10 years, and that's just studying receivers as I always do. I did it for nine years in the NFL. The guy runs every single route, and he makes it look easy."

USC's loss at Stanford last season also was the breakout game for Woods, who had 12 catches for 224 yards and three touchdowns. The sophomore has risen to a spot among the sport's top receivers this season, ranking second in the nation with 72 catches and 128.9 yards receiving per game along with eight TDs.

"Let's be real, it's out there: He torched us last year," Stanford safety Michael Thomas said. "That did motivate us to play better, because we would like to think that we're not the type of secondary that just gives up big yards and just allows any type of receiver to come in and destroy us like that. And it's definitely motivation for this week."

Top 25 schedule

Today's games

No. 3 Oklahoma St. vs. Baylor, 1:30 p.m.

No. 4 Stanford at No. 20 USC, 6 p.m.

No. 6 Clemson at Georgia Tech, 6 p.m.

No. 7 Oregon vs. Washington St., 1 p.m.

No. 8 Arkansas at Vanderbilt, 10:21 a.m.

No. 9 Mich. St. at No. 13 Neb., 10 a.m.

No. 10 Kan. St. vs. No. 11 Okla., 1:30 p.m.

No. 12 Wisconsin at Ohio State, 6 p.m.

No. 14 S. Carolina at Tenn., 5:15 p.m.

No. 15 Va. Tech at Duke, 10:30 a.m.

No. 16 Texas A&M vs. Missouri, 10 a.m.

No. 17 Michigan vs. Purdue, 10 a.m.

No. 19 Texas Tech vs. Iowa St., 5 p.m.

No. 21 Penn St. vs. Illinois, 1:30 p.m.

No. 22 Georgia vs. Florida, 1:30 p.m.

No. 23 Arizona St. vs. Colo., 4:30 p.m.

No. 25 W. Virginia at Rutgers, 1:30 p.m.