BERKELEY, Calif. — Oregon’s mistakes and costly turnovers on offense are perplexing for third-year coach Mario Cristobal, because it just hasn’t been this way in recent seasons.

Five lost fumbles and four interceptions in four games. The Ducks have discussed the problems as a team, as position units.

“That is one of the more disappointing things. We’ve been really good about not turning the ball over here for a couple of years,” Cristobal said. “This year we’ve gotten careless. … The things that have caused it have been mental effort-oriented, detail-oriented that can and will be eliminated with work and more effort and more attention to detail. Those things are frustrating, they’re disappointing and our players are upset about it.”

Oregon (3-1) will try to clean up the miscues and learn from a 41-38 loss to rival Oregon State last week that dropped the Ducks from ninth in the AP poll to No. 21. The loss cost the Ducks whatever shot they had at a spot in the College Football Playoff after they had been ranked 15th in the first CFP rankings but are now 23rd.

The realistic goal now as they prepare to face California on Saturday is a Pac-12 championship.

The winless Golden Bears (0-3) have had their own issues with special teams. They had a would-be tying extra point attempt blocked in the waning moments of a 24-23 loss to rival Stanford in the Big Game last Friday in Berkeley.

The next daunting test on their home field is with the Ducks, who are coming off their demoralizing late defeat.

Oregon quarterback Tyler Shough threw for 266 yards and two touchdowns with two interceptions last week. He has four interceptions in all.

The Ducks’ run defense had few answers for Oregon State star Jermar Jefferson, who went off for 226 yards and two touchdowns, one of those a career-best 82-yard TD run.

Cal running back Christopher Brown Jr. has been limited in his touches by an injury but coach Justin Wilcox was hopeful he would continue to get more reps this.