SANTA CLARA, Calif. -- The San Francisco 49ers gave up 453 yards to Ben Roethlisberger and the Steelers on Sunday.
The last time they allowed that many was in December 2013, against their next opponent, the Cardinals and quarterback Carson Palmer.
For the 49ers (1-1) to rebound this week in Arizona, they must prevent the big play, which was their Achilles' heel in last week's 43-18 loss in Pittsburgh.
Roethlisberger amassed 369 yards passing against the new-look 49ers, causing most of his damage on six plays that averaged 45 yards. Palmer has a similar penchant for throwing the ball deep, giving San Francisco's defense a chance to correct its mistakes in its first divisional game of the season.
"It's such a copycat league," 49ers defensive coordinator Eric Mangini said. "It's like anything else, whenever you get hit on something, they're going to try to hit you again, and the next team will and the team after that will."
The first-place Cardinals (2-0) enter Sunday with the NFL's highest-scoring offense after putting up 31 and 48 points in their wins over the Saints and Bears. They're led by Palmer, owner of the league's third-best quarterback rating, and his slew of talented receivers.
Since 2013, the Cardinals are 18-6 with Palmer as starting quarterback. Last season, Palmer was limited to six games after suffering a torn anterior cruciate ligament in his left knee during a November win over the Rams.
But now he's back after an offseason of rehabilitation and playing some of the best football of his career, Cardinals head coach Bruce Arians said.
"He's probably playing at a level right now probably as good as anybody I've ever coached," Arians said. "He's a film-watching fool."
After allowing three points in the season opening win over the Vikings, the 49ers secondary and pass rush struggled against the Steelers.
Second-year cornerback Kenneth Acker, who missed his entire rookie season with a stress fracture in his foot, allowed six catches in coverage against receiver Antonio Brown, who finished with nine receptions for 195 yards and a touchdown.
Slated to go up against talented receivers Larry Fitzgerald, John Brown and Michael Floyd, Acker will continue to get tested during his first season in the starting lineup.
"I just look at it is as a challenge," Acker said. "I know the ball is going to come. It's what they do. I know they're not going to skew away from what they've been doing because it's been effective and it works for them."
San Francisco was unable to sack Roethlisberger on Sunday, marking the first time the 49ers failed to get a sack since last October's win over Kansas City.
Palmer has yet to be sacked this season, in part, because of his ability to move around in the pocket.
"I think the thought process that he's a statue, that's not the Carson I've experienced," Mangini said.
Game notes
49ers RB Reggie Bush missed practice Wednesday and Thursday to rehab his strained left calf. He suffered the injury in the first quarter of the opener against the Vikings and did not travel to Pittsburgh while he continued treatment. ... RB Carlos Hyde (leg), TE Vance McDonald (leg), TE Blake Bell (back) and WR Torrey Smith (leg) all sustained contusions against the Steelers but returned to practice this week. ... The NFL announced Thursday that former Australian Rugby League star and 49ers RB Jarryd Hayne has the league's fifth-highest selling jersey since Sept 10.
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