Center Rodney Hudson was placed on injured reserve by the Kansas City Chiefs with a right knee injury suffered in the second half against New Orleans on Sunday.
Hudson walked off the field to the bench under his own power, but was then taken off the field on a cart.
Offensive linemen Russ Hochstein and Bryan Mattison were signed. A veteran of 138 games, Hochstein has spent time with Denver, New England and Tampa Bay over 10 NFL seasons. Mattison is a center who has played in 15 regular-season games with four starts in two NFL seasons. He was with Baltimore in 2010 and St. Louis last season, and spent two years on the Ravens' practice squad.
When Hudson was injured against the Saints, veteran Ryan Lilja was forced into his first regular-season action at center with rookie Jeff Allen taking over at left guard.
Lilja ended up handling 52 snaps, with 17 of those in the shotgun. He also had his first experience at center in one of the loudest stadiums in the NFL.
But nothing seemed to bother the grizzled veteran Lilja.
"We repped it with crowd noise all week in practice so we were ready for that," said Lilja. "That's why you do it. I'm thankful we did do it. It's something we practice every day; you just never know if and when I'm going to have to do it.
"It was tough seeing Rodney get hurt. It was pretty awkward there at first. I had my share of screw-ups, but we got it figured out."
Just as impressive as Lilja's move to center was the play of second-round draft choice Allen in those 52 snaps. There appeared to be no drop in production and protection with the rookie playing.