Matt Barkley hasn’t beaten Stanford in his entire career as a Trojan. He was quarterbacking USC in 2009 for the “what’s your deal” game, when then-head coach Jim Harbaugh went for the 2-point conversion at the end of a 55-21 blowout. Barkley was there for the heartbreak of Stanford nailing a last-second game-winning field goal in 2010. And he was at the helm for Southern California’s three-overtime loss to Stanford last season.

Barkley opted to pass on the NFL draft in favor of trying to win a National Championship, but along the way he’s got some unfinished business to handle with the northern California team that’s had his number.

‘‘It’s just another game,’’ Barkley said, downplaying the revenge angle. ‘‘It’s the next game. It’s Week 3. We’re going up north for an away game. Nothing special about it.’’

Barkley’s last chance to snap the losing streak certainly also ranks as his best. Andrew Luck has been replaced by Josh Nunes, and USC is looking like one of the best teams in the nation. Their No. 2 ranking says as much, despite coming into the season as the top ranked team in the NCAA. USC head coach Lane Kiffin isn’t concerned about the drop.

‘‘Whenever I’m tempted to think like that, I think back to two years ago when we were on probation and couldn’t go anywhere,” Kiffin said. “I’m like, if we’re ranked 1, 2, 3, whatever, that’s all a pretty good place to be.’’

USC dropped to No. 2 after Alabama stomped on Michigan, despite the Trojans beating Hawaii 49-10. They held onto the second spot after beating Syracuse 42-29 in Week 2. Stanford, meanwhile, almost fell out of the rankings after squeaking past SJSU 20-17, but jumped up to No. 21 following a 50-13 victory over Duke.

Stanford tight ends remain the key

Levine Toilolo and Zach Ertz were integral in Stanford’s win over Duke, combining to catch five passes for 108 yards and a touchdown. Nunes should look to his big boys again, because they pose the biggest mismatch on the field for USC’s defense.

Toilolo is huge at 6-8/265, and Ertz isn’t much smaller at 6-6/252. USC’s linebackers Hayes Pullard, Lamar Dawson and Dion Bailey are 6-1, 6-2 and 6-1 respectively. This size mismatch should bode well for the Cardinal.

Stalling the Trojans’ march

Stanford has been fantastic stopping the run in their first two games, giving up an average of 49.5 yards per game. However, keep in mind that the Cardinal have yet to face a runner like Silas Redd, who is averaging 6.8 yards per carry so far this season. USC will be starting redshirt freshman center Cyrus Hobbi on Saturday – something that Stanford will look to exploit, not only against the run but the pass as well.

Through the air, USC has what Shaw called “the best college tandem and it’s not even close” at wide receiver. USC’s first touchdown of the season came on their first play — a 75-yard touchdown pass to Marquis Lee off a bubble screen. That’s exactly the type of play that haunted Stanford’s cornerbacks last season.

“We see people trying to challenge us and see if we can tackle in space,” cornerback Ed Reynolds said. “We’ve had a strong emphasis on that since camp, even going back to spring ball. We kind of pride ourselves right now as far as making tackles in the open field and not having any breakdowns.”

That practice will be put to the test on Saturday. Lee and Robert Woods have already combined for 398 yards and 8 touchdowns.