EUGENE, Ore. -- Marcus Mariota didn't show any signs of stage fright in his debut for the Ducks.
The redshirt freshman quarterback made his first start in a real game on Saturday night, passing for 200 yards and three touchdowns in No. 5 Oregon's 57-34 season-opening victory over Arkansas State.
De'Anthony Thomas caught two touchdowns and ran for another while collecting 119 yards in total offense as the Ducks built a 50-10 lead by halftime.
Kenjon Barner, taking over as starter after the departure of running back LaMichael James, ran for 66 yards and two scores.
The Ducks sat most of their starters after the break.
The loss spoiled coach Gus Malzahn's first game as coach of the Red Wolves, who went 10-3 last season and won the Sun Belt Conference title.
Arkansas State senior quarterback Ryan Aplin threw for 304 yards and three touchdowns, including a 72-yard scoring pass to Julian Jones just before the half.
Mariota replaced Darron Thomas, who decided to leave Oregon with a year of eligibility left. Thomas passed for 2,761 yards and a school-record 33 touchdowns last season when the Ducks went 10-2 and beat Wisconsin in the Rose Bowl.
Mariota was on the practice squad last season and was something of a mystery because Oregon closes practices, but he beat out Bryan Bennett for the starter's job in fall camp.
The native Hawaiian had shown promise in the Ducks' spring game with a touchdown pass and two scoring runs - including one TD rush of 82 yards.
Mariota is the first freshman to start in an opener for Oregon since Danny O'Neil in 1991. He completed 18 of 22 passes.
The Ducks scored on their first drive of the game with Barner's 4-yard dash, then added the 2-point conversion to make it 8-0.
Barner, a senior, was James' backup for the past two seasons. James, the school's career leading rusher, left Oregon early for the NFL draft and was a second-round pick by the San Francisco 49ers.
Mariota connected with De'Anthony Thomas with a 12-yard pass to make it 15-0.
Thomas made a splash last season when he set an Oregon freshman record with 18 touchdowns, rushing for seven, nine on receptions and two on kickoff returns.
Before the first quarter was over, John Huff pulled down a 4-yard touchdown pass from Mariota and Barner added a 17-yard scoring run to make it 29-0.
Brian Davis kicked a 43-yard field goal for the Red Wolves early in the second quarter.
Thomas scored twice, once on a 12-yard pass from Mariota and then on a 33-yard run to make it 43-3, and there was still 10:45 left in the half. True freshman Byron Marshall added a 3-yard TD run for the Ducks.
Aplin passed to Jones, who ran down the right side to close the gap a bit with 3:20 left in the half, before Davis opened the third quarter with a 29-yard field goal.
Aplin added a 6-yard touchdown pass to Josh Jarboe before the end of the quarter to make it 50-20.
Bennett, who came in for Oregon in the second half, found Rahsaan Vaughn with a 7-yard scoring pass, before Aplin's two final touchdowns, a 38-yard pass to Carlos McCants and a 1-yard keeper with 4:30 left.
Arkansas State and Oregon had never played each other. Indeed, the Red Wolves had never faced a Pac-12 foe.
The Ducks were familiar with Malzahn because he was the offensive coordinator for Auburn two seasons ago when Oregon faced the Tigers in the BCS championship game.
Malzahn, an Arkansas native, had already hit some snags before his first game as the Red Wolves' head coach. He brought in transfer Michael Dyer from Auburn but had to dismiss him in July after he was pulled over for speeding and a gun and marijuana were found in the car.
Dyer rushed for 143 yards for the Tigers in the national championship game against the Ducks.
Also, Malzahn dismissed wide receiver Earl Lucas and suspended WR Tres Houston for violating team rules.