Oregon's defensive line was so depleted that backup tight end Koa Ka'ai and two other freshmen were pressed into emergency duty.
Big-play running back Kenjon Barner was bottled up all night so freshman quarterback Marcus Mariota put the game on his arm.
Oregon overcame numerous hurdles to beat California 59-17 on Saturday night to move into the top spot in The Associated Press poll with just three weeks left in the regular season.
"That's always been our philosophy," coach Chip Kelly said of the "next man up" mantra. "We really got tested with it today. Our guys did a nice job. I can't say enough about what that young defensive line did."
The Ducks (10-0, 7-0 Pac-12) were without four of their top five linemen coming into the game and then lost defensive tackle Taylor Hart in the first quarter to another injury.
While Isi Sofele and the Golden Bears (3-8, 2-6) were able to run the ball effectively for 2½ quarters, freshman Arik Armstead forced the interception that turned the momentum in the third quarter and the banged-up defense kept Cal off the scoreboard for the final 25 minutes of the game.
"Just because they're low on the depth chart doesn't mean they're not going to play," safety Brian Jackson said. "They showed that today. They were able to step in with the big boys. They came in and we didn't see any letdown. I saw different numbers and different names in front of me but I didn't see any difference in the play."
The Ducks survived the litany of injuries to the front four and a possibly season-ending injury to safety Avery Patterson to win their 13th straight game and move into the top spot in the poll following Alabama's 29-23 loss to Texas A&M earlier in the day.
The only other time the Ducks held the top ranking came in 2010, when they were No. 1 for seven weeks before being passed by Auburn late in the final regular season poll in 2010.
Oregon, No. 2 Kansas State and third-ranked Notre Dame are the only undefeated FBS teams left who are eligible for the postseason and are fighting for the two spots in the BCS title game.
But that's not what the Ducks are worried about right now.
"That's what's so good about this team," said Josh Huff, who had three TD catches. "We don't pay attention to the rankings and what's around us. We just play Oregon football. We'll pick our heads up in December and we'll see where we're at."
Before that happens they need to navigate a treacherous closing stretch of the schedule, starting with a home game next week against No. 14 Stanford. A visit to No. 15 Oregon State and a possible spot in the Pac-12 title game follow, but the big concern now is the Cardinal and their powerful running game behind Stepfan Taylor.
The Bears rushed for 236 yards — the most allowed all season by the Ducks — with most of the damage coming in the first three quarters.
"It was getting a little frustrating," Jackson said. "Stanford is a running team. We know what to expect next week."
What made those losses on defense easier to overcome was the strong performance by Mariota. Most of the focus on the Ducks offense was on Barner last week after he rushed for 321 yards and five touchdowns against Southern California.
But he never got going against a Cal defense focused on shutting down the run and even left the game briefly with a right hand injury that he refused to talk about after the game.
Barner was held to 65 yards rushing on 20 carries — his lowest output against an FBS team this year — and the Ducks managed a season-low 180 yards on the ground, their lowest total in a conference game since 2010.
But with Mariota throwing for a career-high 377 yards and a school record-tying six touchdowns, the Ducks still managed to set a major college football record by scoring at least 40 points for a 13th straight game.
"At the end of the day we still had a good game," Barner said. "I'm not the type of person that has to be the guy. Josh Huff deserved everything that came his way tonight. Marcus continues to impress, guys just continue to step up and do their job. As far as me having a tough game, I'm not worried about it. We came out with a win. That's the most important thing."