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Arizona State had two returning starters and plenty of questions on defense heading into the season. Even coach Todd Graham was unsure what to expect, calling his group talented but unproven.

There weren't many answers early in the season and even more questions when UCLA ran over the Sun Devils on Sept. 25.

But since that game, the true nature of this defense has revealed itself: These guys are pretty good.

Good enough, in fact, to be the springboard for No. 11 Arizona State's bid for a Pac-12 championship and, possibly, a spot in the College Football Playoff.

"It's almost opposite, it's kind of flipped; third game of the year (UCLA), the sky's falling, you graduated nine guys on defense, let's just fold up, we're playing for next year," Graham said Monday. "We're not ever going to do that. We've worked hard."

It just took them a little while to get going.

Arizona State went into the season having to replace almost its entire defense, including two-time Pac-12 player of the year Will Sutton and linebacker Carl Bradford, both now playing in the NFL.

The defense held up well the first three games of the season, though against weaker opponents. The Sun Devils appeared to be exposed in the 62-27 loss to UCLA, giving up 580 total yards while showing no sign of being able to stop an explosive offense like the Bruins.

Arizona State needed a Hail Mary to pull out a wild victory over Southern California the following week, but has ridden its defense to three straight wins since then.

The Sun Devils got their defensive roll going with a gratifying win over Stanford, becoming the first team to shut the Cardinal out in the first half in 87 games while holding them to 288 yards.

Arizona State had a similar result in a road win against Washington, holding the Huskies to 290 yards, and went toe-to-toe with physical Utah in a 19-16 overtime win over the weekend.

"I just think we have a swagger about ourselves," Arizona State safety Damarious Randall said. "Once that swagger gets established, we just swarm the ball and everybody trusts each other."

A big part of Arizona State's defensive success has been its improvement against the run.

The Sun Devils were one of the nation's worst teams against the run early in the season, allowing four straight opponents to rush for over 200, including 232 by Colorado.

Since then, Arizona State has closed in around teams' running games, shutting off lanes and, perhaps more importantly, preventing big plays.

Stanford manhandled the Sun Devils in two games last season, including the Pac-12 Championship game, but the Cardinal managed 76 yards on 22 carries in ASU's 26-10 win on Oct. 18.

Utah's Devontae Booker, the Pac-12's second-leading rusher, had 146 yards against the Sun Devils on Saturday, but had to work for it, needing 37 carries. Arizona State also prevented him from breaking off any big runs, his longest a 16-yard carry in the third quarter.

"If you can't stop the run or you can't run the ball on offense, you're going to struggle to be consistent," Graham said. "The reason why we've gotten so much better is that fundamentally we've gotten better and we've kind of figured out some personnel stuff that's helped us, too."

The defensive surge has put the Sun Devils right where they want to be: In control of the Pac-12 South and in contention for the playoffs.

Arizona State (7-1, 5-1 Pac-12) was No. 14 in the initial playoff rankings and will likely move up when the committee releases its latest rankings Tuesday night.

And the Sun Devils have a huge opportunity in front of them. Next up is No. 8 Notre Dame, which should move up from 10th in the initial playoff rankings.

With both teams entering the game with one loss, it essentially will be a playoff elimination game in the desert Saturday night.

"This is arguably the best football team we've seen all year and with that comes great opportunity," Graham said. "I don't have to give our players any motivational speeches this week; they're going to be pretty fired up to play."

Unlike early in the season, when the offense was primarily carrying the load, the defense should be ready to go.