The Ravens will place center Jeremy Zuttah on injured reserve due to a partially torn pectoral muscle, which will be operated on immediately.
Zuttah's streak of 65 straight games played, the fifth-longest streak in the NFL among interior lineman, will come to an end.
Zuttah marks the 17th Raven placed on injured reserve, which is the second most in the NFL behind the Pittsburgh Steelers (19).
The Ravens could have opted to let Zuttah sit out in hopes that the pec would heal without surgery, but they opted to give him the most time possible to make a full recovery before next season.
"We can't say 100 percent that it would heal like they want it to if we took time and waited, so we're going to go ahead and get that done," Head Coach John Harbaugh said.
Zuttah suffered what could be classified as a strain in the Week 8 win against the Chargers. He took time to rest and recover the pec over the bye, but suited up last week against Jacksonville and aggravated the injury.
"[That] probably tore it a little more than it was before," Harbaugh said.
With Zuttah out, the Ravens will get a good look at second-year lineman John Urschel, who Harbaugh announced will take over as the starter and be backed up by Ryan Jensen.
For Urschel, there are mixed emotions of getting a chance to prove he can be a starting offensive lineman as well as seeing his teammate go down. Even now that he's out, Zuttah told Urschel to reach out to him whenever with texts. He's looking over film for Urschel.
"I love Jeremy," Urschel said. "He's very much still a big mentor for me."
On Wednesday, Urschel joked that he thinks he got "a rep or two" at center in college. Center is an adjustment from playing his natural guard position.
Urschel struggled with several shotgun snaps when stepping in for Zuttah against the Chargers. Since then, he's been working on his shotgun snaps a lot in practice, including with long snapper Morgan Cox, and said he's changed some of his mechanics.
Urschel will have the difficult task of blocking Rams defensive tackle Aaron Donald, the reigning NFL Defensive Rookie of the Year who has six sacks this season, in his first career game as a starting center.
"Not just Donald," Urschel said. "We've got 99 [Donald], we've got 90 [Michael Brockers], we've got 98 [Nick Fairley]. [They are] all first-round talent. So, they've got a very good defensive front, and I'm excited for the opportunity."
The Ravens promoted running back Terrance West from the practice squad, an intriguing move that will give the former Towson standout another shot to break out.
West was a prospect the Ravens liked and targeted in last year's draft, but he was picked by the Cleveland Browns before Baltimore came on the clock in the third round.
After one season, the Browns traded West to the Tennessee Titans. When West was released by the Titans two weeks ago, the Ravens pounced.
West will join Justin Forsett, rookie Javorius Allen and Raheem Mostert, who has been the team's kickoff returner, in the Ravens backfield.
Baltimore re-signed tight end Konrad Reuland to the practice squad to take West's place.