The San Francisco 49ers are headed into a critical NFC West showdown with the Los Angeles Rams this weekend. The team has been able to overcome injuries thus far and remains one of just two undefeated squads in the NFL. The big question is if they can keep it going.

Two new injuries crept up this week. The offense was already without starting left tackle Joe Staley, and the defense played on Monday night without starting cornerback Ahkello Witherspoon. Justin Skule has been doing a good job filling in for the former while Emmanuel Moseley held his own in place of the latter against the Cleveland Browns.

Then the 49ers learned that their other starting tackle, Mike McGlinchey, and only fullback on the roster, Kyle Juszczyk, would miss four to six weeks with knee injuries. San Francisco will have to find a way to overcome those losses and prevail on the road against a division rival.

Head coach Kyle Shanahan joined KNBR on Thursday, as he does every week during the season, and discussed his team's latest injuries, including what they mean for his offense.

"I think it's pretty documented how big a part of what Juice (Juszczyk) does for us," Shanahan said on the "Tolbert, Krueger and Brooks" show. "Of all the stuff we do in the run game schematically and everything, Juice plays a huge factor in that. It's been a little bit of a challenge this week, but we're getting there, working some other guys at some spots, and trying to do a few different things.

"That tackle stuff is a little bit different. I've been coaching a long time, and I never coached a game with a fourth tackle, and for the next four to six weeks, we're playing with our fourth and fifth tackles (the 49ers lost Shon Coleman for the year). So it is going to be a little bit more of a challenge.

"The more you can run the ball and stuff, the more it helps because you don't put those guys in some borderline impossible situation. When you play good team football, it makes it a lot easier, but you always want to make sure that you don't get in a game that gets out of hand because that's when that can be extremely tough for those guys."

You can listen to the entire conversation with Shanahan below.