EUGENE, Ore. -- California wasn't ready for the Oregon rain or the Ducks' offense.
The nation's No. 2-ranked team took advantage of five turnovers by the Bears in the first quarter to blow past Cal 55-16 on Saturday night in a Pac-12 game at Autzen Stadium.
The Ducks improved to 4-0 with a win in their conference opener and exceeded 50 points for the fourth straight game, the first time that has happened in school history.
Oregon lost one of the nation's top all-around threats when De'Anthony Thomas was injured on the opening kickoff, but that did not slow down the Ducks. Thomas said he suffered an ankle injury that was "pretty sore" after the game, but he was not sure of the severity of the injury.
Heavy rain and fierce winds arrived just as the game started and contributed to California (1-3) fumbling on its first four possessions, with Oregon scoring after two of the turnovers. The Ducks turned five first-quarter turnovers by Cal into a 27-0 lead and stretched the margin to 41-0 by late in the first half.
"That was just as bad of a performance as you could have in a lot of different ways," Cal coach Sonny Dykes said.
Oregon sophomore quarterback Marcus Mariota was 11 of 25 for 114 yards and two touchdowns and ran for 33 yards and a touchdown. Sophomore Byron Marshall, who started in place of Thomas, ran for a career-high 130 yards and two touchdowns.
"I wasn't thinking I would get that many carries in the first half, but I don't control that," Marshall said. "De'Anthony got hurt, unfortunately, and I had to hop in and do the best I could."
Bralon Addison scored two touchdowns on punt returns for Oregon.
"It's a great feeling," Addison said. "All season long we had a couple go a long way, but some guys missed a couple blocks or sometimes I would go the wrong way. Tonight, we got it done at the same time. The guys did a great job blocking downfield on the punt return and I ran the right return."
After Oregon built a 41-3 lead at halftime, Addison returned a punt 67 yards for a touchdown in the second minute of the second half. Running back Thomas Tyner added a 21-yard touchdown run to push the lead to 55-3 in the third quarter.
Jeffrey Coprich had a touchdown run for Cal midway through the third quarter before Zach Kline threw a touchdown pass to James Grisom in the fourth quarter.
Oregon took the opening drive 58 yards in less than two minutes before scoring on a 14-yard run by Marshall to open a 6-0 lead.
Cal fumbled on its first four possessions in the first quarter as rain was falling sideways and Oregon turned two of those turnovers into touchdowns.
Oregon took over at the Cal 32-yard line and scored five plays later when Mariota threw a 19-yard touchdown pass to Josh Huff to put Oregon ahead 13-0 with 8:56 left in the first quarter.
Cal quarterback Jared Goff fumbled on the next play and Oregon recovered at Cal's 22-yard line. On fourth-and-2, Mariota found Daryle Hawkins for a 14-yard touchdown pass to push the Ducks ahead 20-0 with 7:16 left in the quarter.
Cal's first possession that didn't end with a fumble instead ended with a punt that gave Oregon the ball at Cal's 38-yard line. Four plays later, Marshall scored on a 9-yard run to put Oregon ahead 27-0 late in the first quarter.
Goff, who entered the game leading the country with 435.3 passing yards per game, was taken out late in the first quarter after he completed 3-of-6 passes for 11 yards.
"It was very disappointing," Goff said. "We were really trying to come out fast this game and it was really disappointing to come out the way we did. That's mainly on me."
He was replaced by redshirt freshman Zach Kline, who threw an interception for Cal's fifth turnover of the first quarter.
Mariota opened the second quarter with a 2-yard touchdown to push Oregon's lead to 34-0.
Bralon Addison returned a punt 75 yards for a touchdown as Oregon made it 41-0 with 6:08 still left in the first half.
California's Vincenzo D'Amato got Cal on the board with a 46-yard field goal as the first half ended to get the Bears within 41-3.
Oregon finished with 264 yards rushing and 381 total yards.
Kline finished 18 of 37 for 165 yards and one touchdown as Cal totaled 325 yards of offense.
"Our defense was awesome," Oregon coach Mark Helfrich said. "They set the tempo in that regard. It was an outstanding effort for the defense."
NOTES: Oregon TE Colt Lyerla, who missed the last game with an illness, returned to the lineup. ... Cal has played three ranked teams in its first four games. The Bears opened with a 44-30 loss to No. 22 Northwestern and also lost to No. 4 Ohio State 52-34 before playing the Ducks. ... Oregon has not lost a conference opener since 2005.