SANTA CLARA -- Quarterback C.J. Beathard sustained a knee contusion and a hip strain Sunday that could limit his practice time this week, 49ers coach Kyle Shanahan said.
Beathard's injury is not expected to keep him out of action for long, though his availability for this week could be in question. Shanahan said he would make a decision by Wednesday whether Beathard or Jimmy Garoppolo will start Sunday against the Chicago Bears at Soldier Field.
"To give those guys the best chance to be successful, you want to give them all the reps, which still isn't enough reps," Shanahan said. "Any time you split those evenly, it's kind of a disservice to both. If you need those reps to make a decision, I've done that before in other situations when you have to do it, but that's usually a situation you want to try to avoid."
Shanahan watched film with both quarterbacks on Sunday. The first practice of the week is scheduled for Wednesday.
Garoppolo played three snaps Sunday in the 49ers' 24-13 loss to the Seattle Seahawks. He scrambled for 4 yards, tossed an 8-yard pass to Aldrick Robinson and a 10-yard scoring throw to Louis Murphy.
Garoppolo entered the game with 1:07 remaining after Beathard went down with an injury. Beathard has completed 123 of 224 pass attempts (54.9 percent) for 1,430 yards with four touchdowns and six interceptions and a passer rating of 69.2.
Running back Raheem Mostert (knee) and offensive lineman Erik Magnuson (foot) will go on injured reserve after sustaining injuries in Sunday's game. Mostert sustained a torn medial collateral ligament, which will not require surgery. Magnuson sustained a foot sprain in the first half and played the entire game with the injury.
"He toughed it out, played throughout the whole game. It was a pretty bad foot sprain, so he's going to have to go on IR," Shanahan said. "I was pretty amazed. Got a lot of respect for that guy for staying out there and battling through that, especially with how short we were at tackles.
"You get an undrafted rookie guard out there starting at right tackle for you going against (Seattle defensive end) Michael Bennett playing with a foot sprain for three quarters to where he's not going to be able to play the rest of the year, he doesn't flinch, doesn't hesitate, just keeps playing, doesn’t say anything, that's a guy I'd love to play with.”
Free safety Adrian Colbert is expected to return to practice this week in a limited role. He missed Sunday's game after undergoing surgery a week earlier to repair a broken thumb.
“We'll see how the week goes with him and how it heals and how he feels," Shanahan said. "There is a chance that he could play this week. Feel definitely better about him the following week versus Houston, but there's a chance.”