ATLANTA -- The San Francisco 49ers placed two more defensive starters on injured reserve Saturday as the league's top-ranked defense continues to battle injury attrition.

Defensive tackle Javon Kinlaw (right knee) and cornerback Emmanuel Moseley (torn left ACL) are the team's ninth and 10th players to land on injured reserve this season, though Kinlaw could be one of its eight players designated to return once he has been on the list for at least four games.

Moseley will soon have surgery on the injured knee but won't return in 2022. The move was expected after Moseley suffered the injury in last week's win against the Carolina Panthers.

Kinlaw's situation has been a bit more difficult to read, though he's missed the past two games. He had surgery to repair lingering issues in his right knee in October 2021, a procedure the Niners believed would allow Kinlaw to finally be free of the problems dating to his time at South Carolina.

After the first three games this season, Kinlaw said there was fluid buildup in the knee and that it would have to be managed as the season went on.

Niners coach Kyle Shanahan indicated the recent problems were unsurprising.

"We expected some of this going through the offseason," Shanahan said Oct. 7. "We knew some things would act up on him. It has."

Including linebacker Azeez Al-Shaair (sprained right MCL), the Niners will play the Atlanta Falcons on Sunday with three defensive starters on injured reserve. They will be without at least three more as defensive tackle Arik Armstead (foot, ankle) and free safety Jimmie Ward (broken left hand) have already been ruled out and end Nick Bosa (groin) was made inactive for the game on Sunday.

On Wednesday, the 49ers practiced without all four members of their starting defensive line and only end Samson Ebukam, who missed that session with Achilles soreness, has been cleared to play against the Falcons.

With Kinlaw and Armstead out, the Niners will again turn to veterans Hassan Ridgeway and Kevin Givens to start at the tackle spots.

"They've done a great job with the more reps that they've been given," defensive coordinator DeMeco Ryans said. "I've seen them get better the more they're out there."

Bosa did not practice Wednesday and Thursday but was a limited participant in the Friday session, which the Niners run at more of a walkthrough pace. Shanahan said Friday that the Niners "have to be careful" with Bosa and a groin injury because it could get worse if he plays too soon.

That's especially true for a Niners team that has grown increasingly wary of playing on artificial turf because of the injuries they've had on that surface in recent years.

With Bosa joining Armstead and Kinlaw as out this week, the Niners will turn to a group that includes Charles Omenihu, Kerry Hyder Jr. and rookie Drake Jackson to fill in.

While Moseley and Kinlaw went to injured reserve Saturday, the Niners activated linebacker Curtis Robinson from that same list. He rejoins the active roster after suffering an ankle injury in the preseason.

The team also elevated cornerback Dontae Johnson and receiver Willie Snead IV from the practice squad to the roster for the Sunday game.