A defense transformed from porous to powerful in one season is a major reason Arizona State is 5-0 heading into its Pac-10 showdown at top-ranked Southern California on Saturday.

The heart of that defense for the 15th-ranked Sun Devils is a trio of linebackers -- virtual clones with size, speed and a shared desire to deliver the punishing hit.

The middle linebacker, senior Justin Burks, stands 6 feet 1 and weighs 231 pounds. One outside linebacker, junior Dale Robinson, is 6-1, 236. The other, junior Jamar Williams, is 6-1, 243.

"Those guys are violent. They're all big. They're all physical," safety Emmanuel Franklin said. "When those guys are flying to the ball, it's just violence -- wham, wham, wham."

The Sun Devils, whose open week gave them extra time to prepare for the Trojans, lead the Pac-10 and rank 11th nationally in scoring defense at 12.8 points per game. They lead the league and are sixth nationally in pass defense efficiency (94.6 rating) and are third in the Pac-10 and 20th nationally in rushing defense (98.6 yards per game).

This from a team that went 5-6 a year ago, and gave up 27 points and 404 yards per game.

The defensive turnaround coincides with a switch from a 4-2-5 scheme to a 4-3. Williams, though, feels there's a bigger reason for the new success.

"A lot of guys were happy about the switch," he said. "But the attitude is completely changed on defense. I feel like no matter what defense we're playing, with this type of attitude we can be great."

Burks and Williams were returning starters. Robinson is a transfer from Glendale Community College who had to earn his starting job in training camp.

"Dale was a great surprise," defensive coordinator Brent Guy said. "We didn't realize we had quite the player we had in him. We knew we had a great blitzer, but we didn't know we had a guy who could play on the run downs and all those other downs."

Robinson quickly developed a chemistry with the other linebackers.

Together, the linebackers have accounted for 35 percent of the team's tackles. In the team's victory at Northwestern on Sept. 11, they had 29 of 69 stops.

Robinson was Pac-10 defensive player of the week with his 14 tackles, 10 of them solo, against Northwestern. Williams earned the same honor after five stops, four solo, a tackle for loss, a sack and an interception in the victory over Iowa.

The three have developed a bond that has led to some intense, but friendly, competition.

"We're real cool. We're real close," Robinson said. "We're not afraid to say something if one of us is messing up. And if Jamie makes a good hit. Then we want to make a big hit on the next play."

Burks, the only one of the three yet to get a conference player-of-the-week award, had a career-best 13 tackles in the victory over Oregon State, when Arizona State held the Beavers to minus-19 yards rushing.

"We always compete in whatever we do -- in football, even video games," Williams said. "Me, Justin and Dale, we have a lot of fun."

All three were added this week to the watch list for the Butkus and Lombardi awards.

"Those three linebackers are playing great," Coach Dirk Koetter said. "Those guys can all run and hit. They are guys who can really bring it."

The linebackers know they will face by far their biggest challenge against the Trojans in front of a crowd of 90,000 or more.

"You're playing the number one team. That kind of stuff motivates you," Williams said. "You've got Reggie Bush, Matt Leinart, LenDale White. You've got good receivers. They're going to be something we've never seen."

The three friends plan to be up for the challenge.

"The bye couldn't have come at a better time," Williams said. "To go 5-0, get a week to heal up and get extra days of practice, then get to play the number one team in the country, I think anybody would love that schedule."

Arizona St.'s Justin Burks (5) is in a familiar pose, chasing down a runner, in this case Iowa's Jermelle Lewis. Burks, Dale Robinson and Jamar Williams, all linebackers, lead the defense.