LOS ANGELES -- Running back Damien Williams, who suffered a rib injury in the season opener Sunday against the Saints, was placed on injured reserve Saturday.

On Friday, he was declared out of the game Sunday after not practicing all week. His injury apparently is more seriously than he thought.

Defensive tackle Abdullah Anderson and running back Caleb Huntley were promoted from the practice squad to the 53-man roster.

The Falcons (0-1) are set to play the Rams (0-1) at 4:05 p.m. Sunday at SoFi Stadium.

With Williams out, the Falcons were thin at running back. Huntley led the team in rushing during the exhibition games. Also, rookie Tyler Allgeier is available. He was inactive for the Saints’ game.

Williams had a 300-pound player on his back and fell on the football.

“An ugly sight,” Williams said Monday. “It’s a part of the game. You have to take the bruises. Get up and shake it off.”

He went back in briefly to try to give Cordarrelle Patterson a break. Patterson had 22 carries for 120 yards and a touchdown.

Williams had hoped to play against the Rams.

“Of course, right now, I’m a little sore,” Williams said Monday. “We are going to go through the week and see how I feel and try to keep it running.”

Williams has injured his ribs before.

“That wasn’t the first time that happened,” Williams said. “It happened to me a couple of years ago. Like I said, it comes with the game. You take it. Get through the treatments and get back out there.”

Williams was down on the field writhing in pain after the play.

“You ever had a time when you couldn’t breathe,” Williams said. “I was trying to find it. In that moment, and then you have your pads and everything squeezing on you. When the trainers came out there, I was like, get me up now.”

Earlier in the week, Williams was not worried about whether his ribs were broken.

“Nah, I didn’t think I broke anything,” Williams said. “You can tell the difference. I’ve done that when I was a little kid. You know the difference. You hear it.”

He has to miss at least four weeks, so his injury likely is more than some bruised ribs.