Mariota led the Ducks (2-0) to 59 straight points, completing 23-of-33 passes with no interceptions in the non-conference victory.
Johnny Mundt hauled down five passes -- including two TD grabs -- on his way to 121 yards. Josh Huff made six catches for 125 yards and a touchdown for the Ducks.
De'Anthony Thomas led Oregon's rushers with 86 yards and a TD on 13 carries.
Justin Worley posted 126 passing yards on 13-of-25 efficiency for Tennessee (2-1).