Arizona State (5-2, 3-1) got the start it wanted, forcing a fumble on Oregon's second play and scoring a touchdown on its first.
The Sun Devils wilted after that, unable to make up for the early loss of star defensive tackle Will Sutton or find a way to slow down the Ducks as they raced past.
Taylor Kelly, the Pac-12's pass efficiency leader, threw two interceptions that set up Oregon touchdowns in the first half and had 93 yards on 10-of-18 passing while being chased by the Ducks most of the game.
Arizona State's defense, its anchor through the first six games, allowed 454 total yards, including 48 more rushing than it had the previous four games combined.
Mariota threw for one touchdown, ran for another and had one receiving in his first true road game.
Sun Devil Stadium hadn't been the stage for a game like this for some time, maybe back to 2005, when Matt Leinart, Reggie Bush and No. 1 Southern California beat the Sun Devils 38-28.
Oregon had become the standard for success in the West, winning three straight Pac-12 titles, last season's Rose Bowl and earning a trip to the BCS title game the year before that.
The Ducks may be even better this season, again scoring points quickly and in bunches, with an improved defense to go with it.