In the third quarter, the 49ers ruled out offensive lineman Colton McKivitz with a knee injury. McKivitz was filling in for left tackle Trent Williams, who is recovering from a high-ankle sprain. Jaylon Moore replaced McKivitz in the game.
Shanahan said McKivitz suffered an MCL sprain and will miss some time—possibly six to eight weeks.
"He's going to be out a while; very similar to what [RB] Elijah [Mitchell] and [LB] Azeez [Al-Shaair] have," Shanahan noted.
That means it will likely be Moore at left tackle until Williams can return. Although, the coach added that Daniel Brunskill is "always an option."
As for Williams, there isn't any clarity yet on a potential return date.
"We're checking him week by week," Shanahan said.
In the fourth quarter, San Francisco ruled out Arik Armstead with a foot injury. The defensive lineman missed the team's Week 3 contest against the Denver Broncos due to plantar fasciitis in his right foot and was "questionable" to play against the Rams. Shanahan said Armstead is still being evaluated for a foot/ankle injury, so there isn't any new information there. The coach clarified that the ankle aspect is nothing new and is part of the initial foot injury.
Wide receiver Jauan Jennings suffered an ankle sprain on Monday night.
"He'll be day-to-day this week," Shanahan said.
Shanahan added that cornerback Jason Verrett and safety Jimmie Ward are expected to practice on Wednesday. Verrett (ACL) started the season on the physically unable to perform (PUP) list, while Ward (hamstring) was placed on injured reserve on August 31. That could be good news for an already dominant 49ers defense.
Shanahan added that defensive tackle Javon Kinlaw put up a big fight to play on Monday night. He was among the team's seven inactive players against the Rams.
"He tried to play on Monday, but he wasn't that close to going," Shanahan said. "But he wanted to work out before the game, so we gave him a chance, and we decided it would be a lot safer to wait this week and see how he reacts."