EUGENE, Ore. » Quarterback Marcus Mariota believes the No. 3 Ducks were tested enough through their first three games to be ready for Pac-12 play.

Oregon faced Arkansas State, Fresno State and lower-division Tennessee Tech in its nonconference schedule, defeating all of them handily.

But with several young players, especially on offense, there were questions about whether those opponents gave the Ducks enough preparation for what they’ll face in their conference — especially given some of the league’s surprising early season upsets.

The Ducks showed some complacency in a slow second half against the Bulldogs, and then had 12 penalties for 105 yards against the Golden Eagles last weekend.

"I think these three games have really just helped us grow a little bit and mature a little bit," Mariota said. "There’s still going to be those times when we have those struggling points. But that’s to be expected. I think we’ve got to continue to work through that. We’ve just got to take it day by day."

Mariota himself is a redshirt freshman who was on the practice squad last season while Darron Thomas led the Ducks with a school-record 33 passing touchdowns. The 6-foot-4 quarterback from Saint Louis School beat out Thomas’ backup, Bryan Bennett, for the starting nod this season during fall camp.

In the 63-14 victory over Tennessee Tech, Mariota completed 21 of 28 passes for 308 yards and four touchdowns. He was intercepted once and was sacked once. It was the first time in school history that a freshman QB had thrown for more than 300 yards.

Mariota has thrown eight touchdown passes this season with just one interception, and is completing more than 75 percent of his passes. He is ranked 10th in the nation and first in the Pac-12 with a quarterback efficiency rating of 180.54.

"I feel very comfortable out there. From the first game to now I think my confidence has grown with every game. Just to go out there and get hit, and throw the ball a little bit more, that was good for me," he said. "I’m looking forward to the next one."

But the Ducks make a significant leap in competition this weekend when they host No. 22 Arizona, which is also undefeated through its first three games under new coach Rich Rodriguez.

The Wildcats are one of the league’s teams that pulled off a notable nonconference upset with a 59-38 victory over then-No. 18 Oklahoma State on Sept 8. On the same day, Oregon State beat then-No. 13 Wisconsin and UCLA defeated then-No. 16 Nebraska.

"Absolutely. Of course," Oregon sophomore tackle Jake Fisher replied emphatically when asked if the Ducks were ready for the Pac-12. "We were prepared in fall camp."

Mariota and Fisher are among several young players on Oregon’s offense. Kenjon Barner, starting this season in place of departed running back LaMichael James, and guards Nick Cody and Ryan Clanton are the only senior starters for the unit.

Sophomore center Hroniss Grasu started last season, and versatile sophomore De’Anthony Thomas set an Oregon freshman record with 18 touchdowns, rushing for seven, catching nine and adding two on kickoff returns.

First-time starters include tackles Fisher and Tyler Johnstone and wide receiver Keanon Lowe. Oregon is still rotating tight ends, using sophomore Colt Lyerla and freshmen Pharaoh Brown, T.J. Daniel and Kamehameha Schools’ Koa Ka’ai.

The offense was hurt by the loss of senior guard Carson York, a key team leader, who hurt his right kneecap during Oregon’s 42-25 win over Fresno State. He announced that he needed surgery and his season was over.

"We’re just so young. I don’t think people realize how young we are," offensive coordinator Mark Helfrich said. "Part of it is growing into roles. Part of it is just playing."

But the Ducks, who are known for their speed on the field, are also quick learners, Helfrich said. "Every day with one of these players you see the light bulb come on and they have one of those ‘Aha!’ moments," he said. "Then they’ve got it."