49ers again face potent offense, leaky defense as Bears visit

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The 49ers’ upcoming opponent has a dynamic 1,000-yard running back, a potent passing offense led by a polarizing quarterback and a defense that was one of the worst in NFL history last year, which explains its 8-8 non-playoff season in 2013.

Is there an echo in here?

The Bears, who will visit Levi’s Stadium on Sunday night, share plenty of similarities to the Cowboys, who were dispatched, 28-17, by the 49ers last weekend.

The most striking commonality is their quarterbacks — Jay Cutler of the Bears and Tony Romo of the Cowboys — both of whom have signed contract extensions worth more than $100 million since 2013 because of their unusual playmaking ability. However, their tendency to throw awful interceptions at inopportune times has led to a love-hate relationship with their fan bases.

Last week, as Romo threw three interceptions against the 49ers, Cutler tossed two picks in a 23-20 overtime loss to the Bills. His last interception was a backbreaker: With the score tied at 17 midway through the fourth quarter, Cutler tossed a 3rd-and-1 pass from Buffalo’s 34 across his body, off his back foot and … into the arms of nose tackle Kevin Williams.

The Chicago Tribune headline: “New year, same bad decisions by Cutler.”

Bills cornerback Corey Graham, a former teammate of Cutler, had the first interception against Chicago last week: “(Cutler) can make some dynamic throws, but when it comes down to it, he will give you opportunities to also make plays,” Graham said to the Tribune. “That’s just how he is.”

On Sunday, Cutler, who threw a career-high five interceptions in his only start against the 49ers in 2009, could be without his top two targets: wide receivers Brandon Marshall and Alshon Jeffery.

CHICAGO, IL - AUGUST 14: Jay Cutler #6 of the Chicago Bears looks for a receiver during the first quarter of their preseason agame against the Jacksonville Jaguars at Soldier Field on August 14, 2014 in Chicago, Illinois. (Photo by Jonathan Daniel/Getty Images) less CHICAGO, IL - AUGUST 14: Jay Cutler #6 of the Chicago Bears looks for a receiver during the first quarter of their preseason agame against the Jacksonville Jaguars at Soldier Field on August 14, 2014 in ... more Photo: Jonathan Daniel, Getty Images Photo: Jonathan Daniel, Getty Images Image 1 of / 5 Caption Close 49ers again face potent offense, leaky defense as Bears visit 1 / 5 Back to Gallery

The duo combined for 189 catches, 2,716 yards and 19 touchdowns last year, but Marshall sustained an ankle injury in the season opener and Jeffery left early with a hamstring injury. Neither has practiced this week.

That’s welcome news for a 49ers secondary dealing with injuries to its starting cornerbacks. Tramaine Brock (toe) hasn’t practiced this week and Chris Culliver (concussion) hasn’t been medically cleared.

If the Bears arrive with a depleted receiver corps, they could lean a bit more heavily on running back Matt Forte, who ranks third in the NFL in yards from scrimmage (9,754) since 2008. Forte will face a defense that allowed Dallas’ DeMarco Murray to rush for 118 yards on 22 carries in Week 1.

“It wasn’t good last week,” 49ers defensive coordinator Vic Fangio said. “… We’ll need to play the run a whole lot better.”

The Bears can relate after last year’s defensive disaster. In 2013, Chicago allowed the 10th-most points in NFL history (478), surrendered a league-high and franchise-worst 2,583 rushing yards and ranked 32nd in yards allowed per rushing attempt (5.3).

The Bears dealt with their share of injuries: For example, two Pro Bowlers, cornerback Charles Tillman and linebacker Lance Briggs, combined to miss 15 starts. There were also personnel deficiencies. They attempted to address their leaky defensive line in the offseason by signing a trio of free agents: Jared Allen, Lamarr Houston and Willie Young.

“It’s completely new players up there,” 49ers offensive coordinator Greg Roman said. “That’s really the biggest thing.”

The Bears, however, got the same old results in Week 1. Buffalo rushed for 193 yards, averaged 5.8 yards per attempt and had runs of 13 and 38 yards on its winning drive.

“When you give up that many rushing yards, it's embarrassing. What can I say?” Allen said to the Chicago media. “It all starts with the run game. I know this league is about sacks and rushing the quarterback, but you do not win unless you stop the run.”

Eric Branch is a San Francisco Chronicle staff writer. E-mail: ebranch@sfchronicle.com