Programming note: For comprehensive 49ers coverage from Santa Clara, watch SportsNet Central tonight at 6, 10:30 and midnight on Comcast SportsNet Bay Area.
SANTA CLARA -– Starting cornerback Tramaine Brock, who spent the early part of Friday’s practice in the weight room on a stationary bike, is not expected to play Sunday night against the Chicago Bears due to a sprain to the big toe on his right foot.
Perrish Cox is expected to make his first NFL regular-season start since his rookie season of 2010 with the Denver Broncos in place of Brock.
Right tackle Jonathan Martin is likely to make his second start in place of Anthony Davis, who remains out of action with a hamstring strain.
Brock and Davis are listed as questionable on the team’s official injury report.
Cornerback Chris Culliver is also listed as questionable, but 49ers coach Jim Harbaugh said Culliver is on track to play. Culliver took part in limited practice Thursday and Friday. He has cleared all but the contact simulation to pass the NFL’s protocol on concussions.
Veteran cornerback Chris Cook, who was inactive for the season opener against the Dallas Cowboys, will make his 49ers debut in a backup role.
Punter Andy Lee made his first appearance on the injury report. He is listed as probably with a right knee injury.
The Bears’ top two receivers, Brandon Marshall and Alshon Jeffery, are both listed as questionable.
C Marcus Martin (knee)
CB Chris Culliver (concussion, stinger)
CB Tramaine Brock (toe)
OT Anthony Davis (hamstring)
P Andy Lee (right knee)
DT Justin Smith (not injury related)
G Matt Slauson (ankle)
C Roberto Garza (ankle)
QB David Fales (right shoulder)
FB Tony Fiammetta (hamstring)
WR Josh Morgan (groin)
WR Brandon Marshall (ankle)
WR Alshon Jeffery (hamstring)