BOULDER, Colo. (AP) Marcus Mariota 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 2 1/2 quarters.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.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.The Ducks trailed for 6 1/2 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 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.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 wasn't an effective formula for an upset, but it did keep the Buffaloes from coming away empty-handed.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 on their first drive after the break when Mariota found Addison uncovered for a 44-yard touchdown and he hit Huff from 26 yards out before calling it a night.Mariota was 16 of 27 for 355 yards with no interceptions and one sack. Addison had 158 yards on five catches and Huff had 103 yards on five receptions.The Buffs couldn't corral the opening onside kick, so Oregon started at the 50-yard line. After forcing a three-and-out, Colorado drove down the field for Oliver's 33-yard field goal.On the Ducks' next drive, senior Buffs linebacker Derrick Webb dropped an interception at midfield and the Ducks breathed a sigh of relief. Mariota threw a 39-yard pass to Huff, setting up his 2-yard keeper for the score. Pharaoh Brown took the 2-point pitch into the end zone for an 8-3 lead.Two plays later, running back Michael Adkins took the handoff and pitched to Richardson, who pulled up and connected with D.D. Goodson for a 75-yard touchdown that gave Colorado a 10-8 lead.Richardson also caught five passes for 134 yards.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. Byron Marshall rushed 23 times for 122 yards and freshman Thomas Tyner added 45 yards on 10 carries and scored from 2 yards out to put Oregon ahead for good at 15-10.Mariota carried seven times for 49 yards as the Ducks piled up 756 yards of offense.The Buffaloes haven't beaten a top-10 team since upsetting third-ranked Oklahoma on Sept. 29, 2007, when Helfrich was Dan Hawkins' offensive coordinator in Boulder___Arnie Melendrez Stapleton on Twitter: http://twitter.com/arniestapletonCopyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.