Bears must establish running game vs. Niners

Based on what we saw Sunday in the season-opening loss to lowly Buffalo, how can the Bears win at San Francisco?

The 49ers have won 36 games over the past three seasons and have played in three straight NFC title games

So the Bears won't do it by using the same 51-18 pass-run ratio coach Marc Trestman called for against the Bills.

Better the Bears should hitch their wagon to two-time Pro Bowl running back Matt Forte, who on just 17 carries against Buffalo produced 82 yards and a 4.8-yard average.

The Bears' best opportunity to upset Jim Harbaugh's team is for Forte to get about twice that many carries.

The offensive line has already been dinged, with center Roberto Garza and left guard Matt Slauson missing the second half vs. the Bills with sprained ankles.

On Tuesday the Bears re-signed guard-tackle Eben Britton, who was waived in the final cutdown, so it's doubtful Garza or Slauson will play vs. the 49ers.

But their replacements, center Brian de la Puente and guard Michael Ola played well after halftime, when Forte picked up 44 yards on 11 carries, and the Bears made up a 10-point deficit to send the game into overtime.

Assuming Alshon Jeffery is less than full speed because of a hamstring injury that kept him off the field during crunchtime Sunday, the wide receiver depth is a concern.

Brandon Marshall fought through a sprained ankle to stay in Sunday's game, but he could also be less than 100 percent vs. the Niners.

That would leave quarterback Jay Cutler to depend on Santonio Holmes, who has been in the system just three weeks, and Josh Morgan.

Micheal Spurlock, who was targeted three times Sunday and had a catch for 8 yards, was cut Tuesday. But he was never supposed to be an integral part of the offense.

Spurlock had just 46 career receptions in his seven previous seasons, when he was primarily a kick returner. Running back Senorise Perry is expected to remain the primary kickoff returner, with Holmes returning punts.

As for the passing game, it will take time for Cutler to get comfortable throwing to Holmes and Morgan since they have limited experience working together.

That was apparent down the stretch Sunday, when Cutler completed 1 of his final 5 passes for 3 yards.

Late in the fourth quarter, when a touchdown would have won the game, the Bears had to settle for a field goal. Then in overtime, 13 of the 16 yards the Bears managed on their only possession came on a Forte run.

In the final 8:01 of regulation, starting with the interception by tackle Kyle Williams, plus overtime, Cutler had a 26.8 passer rating. Three of his last 6 completions went to Forte for 30 yards.

When the Bears have to throw, Cutler should throw it to Forte, who was targeted nine times and had 8 catches for 87 yards.

Maybe the best argument of all for a steady diet of smash-mouth football is that, if run effectively, it will keep the 49ers' super-athletic-freak quarterback Colin Kaepernick and ramrod running back Frank Gore off the field.

The Bears' run defense was trampled for 193 yards by Buffalo. Kaepernick and the 49ers run an even more potent version of the zone read than E.J. Manuel and the Bills.

The last time the Bears played the 49ers was Week 11 of the 2012 season, also in San Francisco, and it could have been titled "A Star is Born."

It was Kaepernick's first NFL start, when he completed 16 of 23 passes for 243 yards, 2 TDs and a passer rating of 133.1. It's unrealistic to expect a Bears defense that failed against Buffalo to contain the 49ers, who have better weapons.

The Bears' best defense Sunday night will be a clock-eating offense.

• Wide receiver Greg Herd was signed to the practice squad Tuesday, and the contract of practice squad defensive tackle Roy Philon was terminated.

• Follow Bob's Bears and NFL reports on Twitter@BobLeGere.