The final stretch of USC’s season begins with perhaps the team’s toughest remaining test when the Trojans travel to face No. 18 Arizona on Saturday.

The Wildcats, despite coming off a lopsided loss to Stanford last week, will challenge the Trojans on both sides of the ball.

Quarterback Nick Foles is the Pac-10’s most efficient passer at 71.8 percent, almost 10 percent higher than second-place Steven Threet from Arizona State. The Wildcats rely on a short, quick passing game at a pace that is only surpassed by Oregon.

Arizona’s defense is no slouch either. Opposing offenses average 17.4 points against the Wildcats. The Trojans are averaging 36.4 yards a game this season, good for third behind Oregon and Stanford.

Foles’ primary target is 6-foot-4, 210-pound wide receiver Juron Criner. With 58 catches for 884 yards, Criner is leading  the conference in receptions, making Foles and Criner arguably the best tandem in the Pac-10.

The Trojans know that any hopes of slowing down Arizona begin by stopping its passing attack.

Senior USC cornerback Shareece Wright said the key is to play with confidence against Arizona’s talented receiving corps, which also includes David Douglas and David Roberts.

“They’re a good group of receivers,” Wright said. “Probably the best that we’re going to see all year so you have to play with a lot of confidence and stay on top.”

USC coach Lane Kiffin spoke about Criner’s skill in practice on Wednesday.

“He’s just special with the ball in his hands,” Kiffin said. “He’s just one of those unique guys.”

Criner caught the game-winning touchdown against the Trojans in the Coliseum last year. During the game, former USC defensive back Josh Pinkard tore his ACL for the third time, which left Pinkard sitting on the couch come draft time.

“Personally, for Josh, I’m going to make sure that [Criner doesn’t score the game-winning touchdown] again this year,” Wright said. “I’ll make sure I do my best to defend that guy.”

On the other side of the ball, not only does Arizona lead the conference in scoring defense but it is also top in defending the run. The Wildcats yield just 2.9 yards per carry and 102.7 yards per game, not to mention they have only allowed eight rushing touchdowns in nine games.

“We just have to be physical,” redshirt junior tailback Marc Tyler said. “Their defensive line pretty much anchors their defense and we’ve got to get those guys out the way.”

—

Kiffin said as of Wednesday he did not yet know who would start at running back against Arizona.

Freshman Dillon Baxter made his first career start against Arizona State last week, but when asked if Baxter would start Saturday, Kiffin said he didn’t know.

It will likely depend on Tyler’s health. Tyler was helped off the field near the end of the Arizona State game after suffering a sprained ankle.

Tyler’s practice activity remained limited on Wednesday, after not practicing Tuesday. The junior said he is not quite at full strength, but the ankle is not bothering him.

As for tailback Allen Bradford’s role in the rotation, Kiffin said the senior has to take care of his injuries and also hold onto the ball before he works his way back in.

“It’s the most important thing we talk about and do here, is take care of the ball,” Kiffin said.

—

Sophomore safety Jawanza Starling and redshirt sophomore offensive tackle Matt Kalil did not practice on Wednesday. Along with Tyler, freshman wide receiver Robert Woods was limited but his status was improving.

“This is the best Robert’s looked this week,” Kiffin said.

Kiffin said there is an obvious dropoff when either Woods or senior receiver Ronald Johnson are less than 100 percent.

“It’s imperative to have [Woods] in our offense, to have the two speed guys out there,” Kiffin said.