By Matt Barrows
DENVER – Teams always insist their bye week has arrived at just the right time. In the 49ers' case, a week off is vital.
The 49ers head into their bye with as many injuries as they've ever had since Jim Harbaugh took over in 2011, including one that will prompt them to groom a new starter along the offensive line.
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Jim Harbaugh said center Daniel Kilgore suffered a broken ankle in the third quarter when an opponent inadvertently landed on the side of his lower left leg. An air cast was placed on the leg before Kilgore was taken off the field in a cart.
The injury forced rookie Dillon Farrell, who went undrafted out of New Mexico, into the game before he, too, left with a sprained ankle. Farrell's injury is not considered serious, and Harbaugh said that Farrell would be in the mix to replace Kilgore.
The top option is another rookie, Marcus Martin, who was a third-round pick out of USC in May. Martin was playing well in the preseason when a dislocated kneecap put him out of action for nearly two months.
Martin, however, recently returned from that injury, and he practiced in full in the run-up to Sunday's game. He did not play against the Broncos because he was one of the seven players the team deactivated for the the contest.
Running back Frank Gore said he was certain offensive line coach Mike Solari would get Kilgore's replacement ready to play when the 49ers' season resumes Nov. 2 against the Rams.
“We wish that (Kilgore) was here, but these things happen,” Gore said.
On defense, the 49ers entered the game without cornerback Chris Culliver, who was dealing with a hamstring strain, then lost another cornerback, Chris Cook, to the same injury. Linebacker Patrick Willis also missed the game with a toe injury and nickel back Jimmie Ward sat out with a strained quadriceps.
“It probably caught up to us today,” linebacker Ahmad Brooks said of the injury bug. “We have a lot of key guys out. That's all I can say.”
Face in the crowd – Colin Kaepernick's birth mother, Heidi Russo, was one of the faces in the crowd Sunday, according to The Denver Post.
Russo, who gave Kaepernick up for adoption when he was five weeks old and she was 19, lives in nearby Thornton, Colo. She and two other women run Three Strands, which serves as a resource for mothers who put their babies up for adoption.
Kaepernick was adopted by Rick and Theresa Kaepernick of Wisconsin before the family moved to Turlock in the early 1990s. Kaepernick has resisted meeting Russo, has been adamant that Theresa is his only mother and has resented media members who have said he should reach out to his birth mother.
"Colin has made his wishes very clear, and I'm just respecting his wishes," Russo told The Post. "... There's never a day you don't think about the child you placed or worry about them or think about them. And that's not a bad thing.”
Tackle's return – Anthony Davis started just his second game of the season for the 49ers at right tackle, and he was part of an offensive line that surrendered a season-high six sacks allowed.
Davis, who was dealing with shoulder and hamstring issues in the offseason, started Sept. 28 against the Eagles but suffered a knee injury in that game.
On Sunday, he mostly faced Denver's top pass rusher, Von Miller, who finished with two sacks, one of them against Davis.
Smith back sooner? -- Before the game, NBC sports reported that Aldon Smith's nine-game suspension could be reduced by one or two games.
Smith has already sat out seven games, meaning he could potentially return for the 49ers' next game, Nov. 2 against the Rams. Smith had been scheduled to return on Nov. 16 when the 49ers visit the New York Giants.
General manager Trent Baalke said Sunday he hadn't heard about the possibility of a reduced suspension. A league source, however, said that it was “a possibility.”
Et cetera – Guard Mike Iupati went through warm-ups with the 49ers' other reserve offensive linemen before the game. That means that Iupati has been cleared for non-contact drills following last week's concussion and only needs to pass a contact-drill test to be cleared entirely.
* Rookie outside linebacker Aaron Lynch got his first NFL sack at the end of the first quarter. Last week's sack for Lynch was given instead to fellow linebacker Dan Skuta.
* Rookie receiver Bruce Ellington, who entered the game with one catch for one yard, had three catches for 44 yards, including a 20-yard touchdown catch from backup quarterback Blaine Gabbert at the end of the game.
* Rookie Chris Borland, who started for Willis, finished with a team-high eight tackles, including a sack.
Read Matt Barrows’ blogs and archives at www.sacbee.com/sf49ers.