EUGENE, Ore. >> Oregon’s Marcus Mariota had no idea he had thrown for more than 400 yards against Tennessee until he got to the locker room after the game and some of his teammates pointed it out.

The low-key sophomore finished with a career-high 456 yards passing, including four touchdowns, in the second-ranked Ducks’ 59-14 victory Saturday.

“It’s pretty cool, I guess,” he said.

Mariota, who completed 23 of 33 passes, was the first Oregon quarterback to throw for more than 400 yards in a game since Kellen Clemens in 2005.

His yardage ties for the third-most in a game in school history, and he easily extended his string of at least one touchdown in all of his 16 games for Oregon. The streak is third among active quarterbacks.

Mariota said it was never Oregon’s plan to throw that much against the Vols.

“It just happened,” he said, “and we went for it.”

To the tune of handing the Volunteers their worst varsity loss since a 48-0 defeat to Mississippi State in 1910.

Freshman Johnny Mundt, who replaced ailing tight end Colt Lyerla, had five catches for 121 yards and two TDs for the Ducks (3-0). Josh Huff added six catches for 125 yards and a score.

Oregon’s sloppy play at the start — four penalties for 35 yards in the first quarter — helped Tennessee (2-1) take an early lead, but it was fleeting and the Ducks led 38-7 at halftime.

Justin Worley completed 13 of 25 passes for 127 yards and a touchdown for the Volunteers, who opened the season with easy home wins over Austin Peay and Western Kentucky. But Tennessee could not keep up with the speedy Ducks, who had 687 yards in total offense compared to 316 for the Vols.

Oregon was the first of a tough stretch for the Volunteers and first-year coach Butch Jones: No. 18 Florida, No. 9 Georgia, No. 13 South Carolina and No. 1 Alabama are among Tennessee’s next five opponents.

“It’s unacceptable whether you lose by two or you lose by what we lost by. We’re here to win,” Jones said. “It better hurt.”

Tennessee drove 80 yards in six plays and scored on Worley’s 4-yard touchdown pass to Jason Croom to go up 7-0.

After Mariota’s 19-yard run got the Ducks to the Tennessee 9-yard line, a fumble and a sack pushed Oregon back to the 15. De’Anthony Thomas appeared to have a 4-yard touchdown catch on fourth down, but it was called back because of pass interference on Oregon and the Ducks settled for a 38-yard field goal by Matt Wogan.

Oregon pulled in front before the first quarter ended with Mariota’s 16-yard pass to Mundt. Lyerla was a surprise absence, apparently because of a stomach virus. Oregon would not confirm the reason for his absence.

After Mariota’s 9-yard touchdown run extended the lead, he connected with Josh Huff who ran untouched for a 54-yard scoring reception. The Ducks went up 31-7 on Mariota’s 45-yard touchdown pass to Daryle Hawkins.

Jones pursed his lips on Tennessee’s sideline while the Ducks’ student section taunted with chants of “S-E-C, S-E-C!” and “We want ‘Bama!”

Thomas added a 28-yard scoring run for the Ducks before halftime. Tennessee defensive lineman Trevarris Saulsberry was helped from the field following the TD, but it was unclear how he was hurt.

Mariota found Mundt again with a 17-yard scoring pass early in the second half. Mundt was the first Oregon tight end with at least 100 yards receiving since Ed Dickson in 2009.

Byron Marshall ran 11 yards for a touchdown to make it 52-7 and Oregon pulled most of its starters on the next series. Freshman Thomas Tyner ran for a 2-yard score to close out the third quarter.

Alden Hill’s 8-yard touchdown run for Tennessee provided the final margin.

Tennessee was without defensive lineman Maurice Couch, who was ruled ineligible for the game while the university investigates allegations he received improper benefits. Yahoo Sports reported that Couch, former Alabama offensive tackle D.J. Fluker, former Tennessee quarterback Tyler Bray, former Mississippi State defensive tackle Fletcher Cox and former Mississippi State receiver Chad Bumphis received payments from Luther Davis, who acted as a go-between for the players with agents and financial advisers.

Chip Kelly was Oregon’s coach three seasons ago when the Ducks visited Tennessee and trailed 13-3 before scoring the game’s final 45 points. The 48-13 loss was the last time Tennessee dropped a regular-season game to a non-conference opponent.

Mark Helfrich, Kelly’s offensive coordinator for the past four years, was promoted to head coach earlier this year when Kelly went to the NFL’s Philadelphia Eagles.

Helfrich agreed that Mariota’s passing yards weren’t necessarily by design, but an offshoot of how the game progressed.

“We tried to set up something early with our formations to validate some of the things we had in the back of our mind,” he said, “and our passing game came alive.”