The Bears will face the 49ers Sunday night without at least three and possibly as many as five starters on their offense due to injuries.

Left guard Matt Slauson (ankle), center Roberto Garza (ankle) and fullback Tony Fiammetta (hamstring) did not practice Friday for the third straight day and were ruled out of the game. Michael Ola and Brian de la Puente will replace Slauson and Garza, respectively.

Meanwhile, ailing receivers Brandon Marshall (ankle) and Alshon Jeffery (hamstring) were listed as questionable on the injury report, meaning they have a 50 percent chance of playing. Marshall did not practice Friday, doing only some light jogging in the walkthrough portion of the workout. Jeffery was limited, taking part in individual drills and some team work.

"I felt pretty good," Jeffery said, "but a practice and a game are different."

The decision about whether Marshall and Jeffery will play Sunday night may not be made until shortly before kickoff. The Bears are slated to fly to San Jose Friday and conduct a walkthrough Saturday at San Jose State University.

"We'll continue to monitor their progress as we work into the game," coach Marc Trestman said Friday after practice. "I'm always optimistic. I'm always going to think positive about it. But we've got time. We'll see where we are. The other [receivers] have gotten a lot of work.

"We'll see where we're at as we move closer. We've got up to 90 minutes before the game to make those kinds of decisions, so we're going to use every minute of it to make sure we're going to make the right decision in the best interest of the team and certainly the player."

After feeling tightness in his injured groin Thursday, reserve receiver Josh Morgan did not practice Friday and was listed as doubtful. The only healthy receiver on the Bears' 53-man roster is Santonio Holmes, who has made steady progress since joining the team Aug. 16.

"He's worked very hard at it," Trestman said. "He's been very diligent spending time before practice, after practice and in walkthroughs with [coaches] in terms of learning what he needs to do in terms of his assignments, so he's doing everything he can to get himself ready."

Because of the injuries, the Bears may have to promote some players from their practice squad. Their practice squad includes two offensive linemen in guard/center Taylor Boggs and guard Ryan Groy, and four receivers in Josh Bellamy, Greg Herd, Rashad Ross and Chris Williams.

"The roster will be ongoing as we move toward game time certainly as we make some of these decisions," Trestman said.