The 49ers took the lead early in the second half and hung on to it without linebacker Patrick Willis, who spent most of the half on the sideline in street clothes with a walking boot on his left foot.
Willis apparently hurt his left big toe late in the second quarter and was one of several 49ers who were sent to the training room Monday. Left guard Mike Iupati, who was being examined for a concussion, and nickel cornerback Jimmie Ward, who injured his quadriceps, also did not finish the game.
Rookie Chris Borland entered for Willis and played alongside Michael Wilhoite, who is substituting for the 49ers’ other star inside linebacker, NaVorro Bowman. It means the 49ers were without their three top linebackers – Aldon Smith is serving a suspension – for the end of the Rams game and that they could be without that trio for Sunday’s game against Denver’s high-powered offense.
Borland, who had two tackles and broke up two passes, received high marks from coaches and teammates.
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“He played great – got his hand on the ball; he was where he was supposed to be,” Wilhoite said afterward. “As a defense, we held them to three points in the second half, so we played well. We fed off our defensive line. They played well, and we basically had to be in the spots where we’re supposed to be in.”
The 49ers did not give a diagnosis for Willis. One possibility is turf toe, which involves a sprained ligament in the big toe. Willis said he’d find out more when he is examined on Tuesday.
Cornerback Tramaine Brock went down with turf toe on an artificial-surface field in Week 1 and hasn’t played since. Brock is likely out until at least after the 49ers’ Week 8 bye.
The 49ers also played most of the second half without Ward, who was injured early in the third quarter.
Perrish Cox filled in at the nickel spot on obvious passing downs while rookie Dontae Johnson played on the outside. Johnson sealed the 49ers’ win with a late interception and touchdown return.
Joe Looney, meanwhile, filled in for Iupati, who was hurt on a short run by Frank Gore in the third quarter. Iupati must pass the league-mandated concussion protocol to play Sunday against the Broncos.
Clutch catch – The injury news was better for wide receiver Stevie Johnson, who took a knee to his backside while fielding an onside kick late in the game. Johnson had to be helped off the field, but he said X-rays showed that the injury may be a deep bruise but nothing that will end his season.
“I’m not counting myself out Sunday at Denver,” he said. “I’ll work with the training staff. I should be ready on Sunday.”
Johnson finished the game with five catches for 53 yards.
Davis not 100 percent – Vernon Davis started Monday’s game against the Rams, but it was clear the tight end was not back to normal after missing the last 11/2 games with a back injury.
Davis finished with three catches for 30 yards. But he also dropped two short passes and was flagged for a false start in the first quarter. Davis said the back pain that forced him out of a Sept. 28 win over the Eagles has subsided somewhat but that he is still dealing with discomfort.
Et cetera – With veteran special teamers Ray Ventrone and Kassim Osgood in uniform, the 49ers deactivated rookie gunner L.J. McCray, who hasn’t had the impact the team hoped for when they kept him on the roster over some veteran players. Fellow rookie Ward took over McCray’s role at gunner.
▪ Kicker Phil Dawson, who booted two field goals beyond 50 yards last week against the Chiefs, knocked one in from 54 yards in the second quarter for the 49ers’ first score of the game.
Dawson is 22 of 25 on kicks of 50 yards and beyond since 2011.
▪ The 49ers allowed no sacks for the first time this season. The Rams still have only one sack on the year.
Read Matt Barrows’ blogs and archives at www.sacbee.com/sf49ers.