SANTA CLARA — The 49ers have followed their defensive script to the letter during the team's 1-1 start: Stop the run and force opponents to pass to beat them.
The NFL's No. 1 rushing defense certainly has done its job. The team's struggling secondary can't say the same.
The 49ers won't alter their approach Sunday when they travel to play the Cincinnati Bengals, part of a 10-day road trip that won't bring them back to California until October.
But they will be making some additions in their defensive backfield that the 49ers hope will make a difference after the team allowed 432 yards passing during last week's overtime loss to the Dallas Cowboys.
Free safety Dashon Goldson did not play in San Francisco's first two games due to a knee injury, and cornerback Shawntae Spencer has played only a handful of defensive snaps as he gradually works his way back from a summer hamstring injury. Both veterans carried streaks of 32 consecutive starts with the 49ers into this season.
San Francisco has been cautious with each player, but after last week's meltdown in the secondary, defensive coordinator Vic Fangio said Goldson and Spencer will be worked into the defensive rotation against the Bengals.
"I'm expecting to start," Goldson said Friday. "I can't say what I can add, but I know what I can do as a football player. I'm another guy out there that can make things happen and be another force on the defense."
The 49ers are looking to force the issue this week against rookie quarterback Andy Dalton after getting shredded last week by Tony Romo, who had 185 yards passing on Dallas' final three drives to rally the Cowboys from a 10-point fourth-quarter deficit to a 27-24 victory.
Dalton, Cincinnati's second-round draft pick, has had a strong start to his NFL career. Dalton set a Bengals rookie record with 332 yards passing last week against Denver, when he also became the second rookie quarterback since the 1970 NFL/AFL merger to record a passer rating of 100 or better in his first two starts.
With Goldson patrolling the deep middle and Spencer getting back in the mix, San Francisco's secondary might have more opportunities to make plays this week.
"You always like to think you can go into a ball game and get turnovers," said Goldson, who led the 49ers with four interceptions and three forced fumbles in 2009. "We saw a couple of plays where (Dalton) forced the ball. We've got to capitalize on a lot of those things, tighten up from what we learned last week and take it into this game."
The 49ers have been playing tight run defense since the season began. They are allowing 54.5 yards rushing per game and just 2.5 yards per carry, a figure that also leads the NFL.
With three new starters among its defensive front seven, San Francisco has picked up where it left off last season, when the 49ers finished sixth in the league in rushing defense and second in yards allowed per carry.
"Our goal at the beginning of every game is to stop the run, and we take pride in that," said inside linebacker NaVorro Bowman, who has 22 tackles in his first season as a starter. "Once you do that, you kind of make a team one-dimensional. We take it as a challenge to stop the run first and then see what they can do in the passing game."