Injuries have plagued the San Francisco 49ers defense in recent weeks. The team hasn't had much rest since its early Week 4 bye, and some believe that may have contributed to the spike in injuries down the stretch.

Whatever the reason, the 49ers aren't making any excuses. They do, after all, own an NFC-leading 11-2 record.

The NFL is a next-man-up league, and the 49ers are no different. They own one of the NFL's best defenses despite dealing with the losses of several key contributors.

Linebacker Kwon Alexander and defensive linemen Ronald Blair and Damontre Moore are among the 49ers players whose season ended early and sit on injured reserve. Defensive tackle D.J. Jones, who is dealing with an ankle sprain suffered during Sunday's win over the New Orleans Saints, could be next.

The defense will be without cornerback Richard Sherman and defensive end Dee Ford for at least a couple of weeks. Defensive end Jullian Taylor (elbow) is out for at least one more game. Safety Jaquiski Tartt is trying to work his way back from a rib injury while cornerback K'Waun Williams is in the concussion protocol and has not practiced this week.

That's quite a list.

Yes, the 49ers defense is banged up. Still, these are no excuses for a unit that prides itself on disciplined play and ferociousness.

Defensive coordinator Robert Saleh was asked on Thursday when the defense might need to change how it approaches a game due to all of the injuries that have plagued the unit in recent weeks.

"Talk to guys like (Dre) Greenlaw, who stepped in for Alexander, or talk to Marcell (Harris), who's stepping in for Tartt," Saleh responded. "They're starters in this league, and that's the way they have to approach it. And so the expectation is that there should be no drop-off. We've got to coach them accordingly.

"There's going to be a little rust that, with Marcell — you saw in the first quarter — a little bit of rust as a starter, to come back in there, and there's an adjustment. If you guys remember, last year, when he stepped in, he just progressed as the year went on. So the expectation for him, and all those guys is that you keep working your tail off to get better every single day, so there is no drop-off.

"That's the mindset, and like we already said, the NFL doesn't care about who's playing. The train's going to keep on moving."

Cornerback Richard Sherman agrees with his defensive coordinator.

"If we've got 11 out there, I expect us to uphold that standard," Sherman told reporters. "I think we have a tremendous amount of depth. I think we trust the guys. I trust Ahkello (Witherspoon). I trust [Emmanuel Moseley]. I just D.J. Reed. Obviously, (I trust) [Marcell Harris] and Jimmie (Ward). I think we can weather any storm with the guys that we have.

"And obviously in the front, we have monsters, and we've got more guys that are going to step up and get more opportunities than they have, and we trust those guys. Sheldon Day will get more opportunities, Solomon (Thomas). We trust those guys to go out there and play at a high level."