Add center Daniel Kilgore to the list of injured 49ers.
Kilgore, who had been having a standout first season as starter along the offensive line, suffered a potentially serious lower-leg injury in the third quarter of Sunday's blowout loss to the Broncos.
"It looks like it might be a break," 49ers coach Jim Harbaugh said after the game.
Kilgore's lower left leg was rolled up on during a Frank Gore run in the third quarter. He immediately signaled to the sidelines for assistance from the team's medical staff and was given an air cast on his ankle before being carted off the field.
In the offseason, the 49ers did not retain former center Jonathan Goodwin, 35, and gave Kilgore a three-year, $5.25 contract extension. He was entering a contract year after being drafted in the fifth round (163rd overall) in 2011.
San Francisco entered Sunday night's drubbing without all-pro linebackers Patrick Willis and NaVorro Bowman, and corner Chris Culliver on defense. Mike Iupati, another former all-pro, who plays one spot to Kilgore's left, also missed the game with a concussion.
The 49ers used a third-round draft pick in May on center Marcus Martin out of USC, who was viewed by many as the top center available. If healthy, Martin would be the favorite to start in Kilgore's spot after the team's bye week against the Rams Nov. 2. He was the final player picked that was invited to the green room at Radio City Music Hall.
Martin suffered a knee cap injury in the preseason before returning to practice in early October. This week was his first full week of practice where he wasn't mentioned on the injury report.
Kilgore's replacement, former undrafted free agent Dillon Farrell, momentarily left the game after rolling an ankle but returned. Harbaugh said Farrell will compete with Martin to replace Kilgore in the starting lineup.
The 49ers' starting offensive line has played just one quarter together all season. Right tackle Anthony Davis made his second start of the year Sunday after missing the first three games with a hamstring strain. He came back to start Week 4 against the Eagles, but sustained an ankle and knee injury on the last play of the first quarter that caused him to miss the team's last two games.
The offensive line allowed six sacks of Colin Kaepernick to the Broncos Sunday, a season high.
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