EUGENE, Ore. -- Heading into halftime locked at 14-all with UCLA, No. 2 Oregon didn't panic. The Ducks knew they'd eventually wear down the No. 14 Bruins. Because that's what they do.
"We understand that our tempo is one of our greatest allies," sophomore quarterback Marcus Mariota said.
Oregon went on to score 28 unanswered points in the second half and beat UCLA 42-14 on Saturday night.
Byron Marshall ran for 133 yards and three touchdowns, Mariota threw for 230 yards and another score, and the Ducks (8-0, 5-0 Pac-12) racked up 555 yards in total offense compared to 283 for UCLA (5-2, 2-2).
"We just had to keep chipping away," Mariota said. "We knew that if we kept getting 5- or 6-yard chunks, we were going to get into a rhythm."
Brett Hundley completed 13 of 19 passes for 64 yards and a touchdown but also threw two interceptions, including one early in the fourth quarter that led to an Oregon touchdown. He also ran for 64 yards and a score.
"That was a very disappointing loss," Bruins coach Jim Mora said. "We didn't come up here to play them close, we didn't come up here to give it the old college try. We came up here to win the game and we didn't get it done and it's very disappointing."
UCLA, which has now lost two straight after falling to Stanford last week, has not won at Autzen Stadium since 2004, and hasn't defeated the Ducks since a 16-0 blanking in 2007. The two teams last met in 2011, when Oregon downed UCLA 49-31 in the inaugural Pac-12 championship game.
The Ducks are the highest ranked opponent the Bruins have faced since they played the No. 1-ranked Ducks in the 2010 season. Last weekend UCLA fell 24-10 to No, 13 Stanford.
Oregon, ranked No. 3 in the initial BCS rankings released last weekend, was coming off a 62-38 victory at home over Washington State. The Ducks have played one other game against a ranked opponent this season -a 45-24 victory over then-No. 16 Washington at Husky Stadium.
"In the first half we had a couple of runs we'd like to have back, and a we had a couple of throws we'd like to have back," Ducks coach Mark Helfrich said. "But we finished right where we wanted to finish."
Oregon got off to a poor start, stymied by its own mistakes and UCLA's stout defense. On the Ducks' second play from scrimmage, Keanon Lowe fumbled a pass from Mariota. The turnover led to Hundley's 4-yard touchdown run to give the Bruins the early lead.
Thomas had missed the last three games after injuring his right ankle on the opening kickoff in Oregon's 55-16 victory over California on Sept. 28, slipping on turf slick from a driving rain.
Thomas was the Ducks' leading rusher with 338 yards and six touchdowns in three games before he was injured. He finished with 31 yards rushing against the Bruins.
Oregon went ahead 14-7 early in the second quarter with a 40-yard scoring run from Marshall, a sophomore who took over as starter in Thomas' absence.
Alejandro Maldonado's punt for the Ducks was blocked late in the half, putting UCLA in Oregon territory. The Bruins capitalized on Hundley's 11-yard scoring pass to Thomas Duarte to even the game at 14.
Midway through the third quarter, Mariota fumbled on first-and-goal at the UCLA 5, but the Bruins were forced to punt and the Ducks quickly responded with Marshall's 11-yard touchdown run.
Avery Patterson intercepted Hundley early in the fourth quarter and the Ducks went on to score on Mariota's 8-yard pass to Bralon Addison. Marshall added a 3-yard touchdown dash with 8:47 left and freshman Thomas Tyner ran for a 2-yard TD with 2:25 to go for the final margin.
It was Marshall's fifth straight game with at least 100 yards rushing this season.
The Bruins were without junior tailback Jordon James, who missed his third straight game with an ankle injury. He had run for more than 100 yards in each of the Bruins' first three games.
The Bruins were also dealing with injuries on their offensive line, and as a result the team started three true freshman: Alex Redmond at right guard, Caleb Benenoch at right tackle and Scott Quessenberry at left guard. The Bruins have played 17 true freshmen this season.
"I told the guys we played hard, but playing hard is not enough. We've got to get to the point of the football where we play efficiently, where we don't make mistakes at critical times, where we run the right route, we block the right guy, we keep the right leverage, we make the tackle," Mora said. "We have to be able to get to the point as a football where we do the things on a consistent basis that champions do. We're not there yet."