Even a slow start couldn't keep Marcus Mariota from calling it an early night.

He threw five touchdown passes and ran for two scores as No. 2 Oregon brushed off some early trickery to rout Colorado 57-16 on Saturday. The Ducks' sophomore connected for two touchdowns each with Josh Huff and Bralon Addison, and played only 2½ quarters.

The man getting so much of the early Heisman hype still hasn't played a full game this season, yet he swears he doesn't mind being a sideline spectator after making quick work of opponents.

"There's three other guys behind me and they practice their tails off all week and I think they deserve to play," Mariota said of backups Jeff Lockie and Jake Rodrigues. "And a lot of us (starters), our goal is to get those guys on the field."

The Buffaloes had Folsom Field in a frenzy when they kept things tight early on, but the crowd didn't like it when Colorado kept going for field goals while the Ducks were piling up the points.

Oregon (5-0, 2-0 Pac-12) has scored at least 55 points in all of its games under first-year coach Mark Helfrich, a former offensive coordinator at Colorado, who took over when Chip Kelly left to coach the Philadelphia Eagles.

He called off the dogs after Mariota's fifth and final touchdown toss with just under seven minutes left in the third quarter, giving him a career high seven total TDs.

"I didn't really think about mercy," Helfrich said. "That's a good program, a proud program. We're not in the embarrassment business. We're not in the statistic business and we don't think about individual awards. That's not our deal. We just wanted to get in a rhythm offensively."

Forcing a three-and-out after the opening onside kick, a 75-yard TD toss from receiver Paul Richardson on a double-reverse and a fourth-down stop had the 40-point-underdog Buffaloes (2-2, 0-2) in the fight early.

"We kind of started off a little slow," Mariota said, "but we started getting things rolling and I'm proud of the guys for fighting through the adversity. I feel like it's going to make us a little better."

The Ducks trailed for 6½ minutes, falling behind 3-0 and 10-8, and they were leading just 15-10 when they got the ball at their 25 with 2:08 left in the first quarter.

Within a minute, they were up 29-10.

Mariota dropped back and saw Addison blowing past his man, and he hit him in stride along the dejected Colorado sideline for a career-long 75-yard touchdown.

After Terrance Mitchell's interception, Mariota connected with Keanon Lowe from 17 yards out for his second TD in 58 seconds, and the rout was on.

"We got Colorado's best shot and we just kept playing through it," Lowe said. "We just kept pushing."

The Buffaloes reached the Oregon 5- and 14-yard lines on their next two drives but first-year coach Mike MacIntyre went for the field goals both times, just as he did when Colorado's first drive stalled at the Ducks 16.

Answering Oregon's touchdown machine with field goals kept the Buffaloes from coming away empty-handed but it wasn't an effective formula for an upset.

"I felt like if we would've kept coming away with nothing, I felt it might have deflated us," MacIntyre said. "I felt that gave us a little bit of energy."

After Will Oliver's pair of chip shots made it 29-16, Oregon went for it on fourth down from the Buffs 27 and 1 and the Ducks converted each time.

Mariota walked it in to make it 36-16, capping a drive that took 3:38, a lifetime by the Ducks' quick-strike standards, and then he hit Huff from 4 yards out to put the Ducks ahead 43-16 at halftime.

The Ducks reached the 50-point plateau for a school record fifth straight time on their first drive after the break when Mariota found Addison uncovered for a 44-yard touchdown.

"We've just got to learn how to start off faster," said Huff, who capped the scoring with a 26-yard TD catch from Mariota. "If we start off faster, there's no one that can stop us but ourselves."

Mariota was 16 of 27 for 355 yards. Addison had 158 yards on five catches and Huff had 103 yards on five receptions.

Richardson caught five passes for 134 yards and threw a 75-yard TD pass to D.D. Goodson after taking the pitch from running back Michael Adams.

Freshman Thomas Tyner's 2-yard TD run put Oregon ahead for good at 15-10.

The Ducks, who came into the weekend as the nation's No. 1 rushing team with a 333-yard average, didn't miss starting running back De'Anthony Thomas, who's out with an ankle injury. Led by Byron Marshall's 122 yards, Oregon gained 350 yards on the ground until Lockie took a knee at the 1 at game's end, leaving them at 349.

Helfrich isn't fretting over the lack of fourth-quarter pressure situations to test his team.

"If we can arrange for however many games we're going to play and they're all like this, we'll take this," Helfrich said.