In leading the Arizona football team to two touchdowns in the fourth quarter against Stephen F. Austin last weekend, a relaxed, unruffled Willie Tuitama showed what he can do when pass rushers aren’t trying to show him the finer points of on-field landscaping.

Keeping the sophomore quarterback upright and able will be perhaps the offense’s biggest challenge Saturday against the deep and formidable front seven of No. 3 USC, which so far this season has shuffled through top-tier talent like Jay-Z’s iPod.

“”The game is so important up front,”” UA head coach Mike Stoops said. “”All 11 (offensive players) are important, but the line of scrimmage – to run the ball, to throw the ball, you got to be able to control some aspect of the line of scrimmage, and that will be key for us offensively. We’ll see if we can hold on.””

The Trojans have been awash in skilled defenders throughout the six-year tenure of head coach Pete Carroll, thanks to three straight national championship game berths and ideal proximity to the best players in the country’s biggest state.

In recent years, though, USC has been known more for its highly touted offensive talent. Former quarterback Matt Leinart and running backs Reggie Bush and LenDale White led the Trojans to titles in 2004 and 2005 and would have captured another in January if not for the efforts of Texas signal-caller Vince Young.

But with Leinart and Co. now advanced to the NFL, USC’s clear strength lies in a defense that, while not statistically dominant through the first three games of 2006 (18th nationally in scoring defense), has the firepower to keep offenses guessing.

Although the Trojans won’t have junior defensive tackle Sedrick Ellis in the lineup because of a knee injury, they will field junior defensive end Lawrence Jackson, who had 10 sacks en route to a first-team All-Pacific 10 Conference selection last season.

And the team has had so much competition at linebacker, where six players who started last season return, that its de-facto base formation has shifted to a 3-4 from a 4-3.

Even with the switch, sophomore linebacker Brian Cushing was converted to defensive end, where he moves from the three-man line to the second level and back again on essentially a play-by-play basis.

“”Coming into the season, I thought their defense would be one of the better defenses in the country,”” Stoops said. “”I think they’re very skilled. I think their linebackers are the best I’ve seen in a long time.””

USC’s impressive personnel will test a Wildcat offensive line that has shown only flashes of consistency with three redshirt freshmen playing significant roles.

With starters Eben Britton (right tackle) and Blake Kerley (center) getting their first career action and right guard Daniel Borg filling out the team’s six-man rotation, Arizona allowed Tuitama to be sacked five times in the team’s first two games.

The most notable hits came on the first offensive series against No. 10 Louisiana State on Sept. 9.

Tigers defensive end Tyson Jackson cut through the line before Tuitama’s first pass and drilled the sophomore with a helmet-to-helmet hit that gave him a concussion and caused him to miss three days of practice the following week.

Tuitama, who was also sacked twice later in that series, played the entire fourth quarter against the Lumberjacks on Saturday and came out unscathed, as SFA didn’t register a takedown on the night.

He credited his 6-of-9, one-touchdown performance to improved protection, and the Wildcats’ line will have to show similar, if not better, resolve to fend off the Trojans’ expected ample pressure.

“”Their front line (has) big, strong guys,”” said Brandyn McCall, a junior tight end. “”If we’re physical, and we execute, we’ll be just fine.””

Sophomore guard Joe Longacre got his second start of the season in place of Borg against the Lumberjacks, and he said facing the Trojans will present a considerable contrast this weekend.

“”I mean, it’s still football, but the athletic ability of those guys – USC’s a very talented team,”” he said. “”There’s definitely a big jump in the talent.””

Starters:

• Dallas Sartz (strong side; 6-foot-5, 240 pounds; redshirt senior): two sacks (played in two games)

Backups:

• Oscar Lua (middle; 6-foot-1; 245 pounds; redshirt senior): 66 tackles (team high), interception