METAIRIE, La. -- Saints running back Mark Ingram will not play Sunday against St. Louis after missing all week with a right heel injury.
As a result, the Saints will move running back Chris Ivory from the physically unable to perform list to the 53-man active roster, coach Sean Payton said Friday.
The move swaps one leading rusher for another.
Ingram leads the Saints with 329 yards and three touchdowns on 85 carries this season. Ivory, meanwhile, led the Saints in 2010 with 716 yards and five touchdowns.
New Orleans must release a player to make room for Ivory, but hadn't announced a move as of Friday afternoon.
Ingram was unavailable for comment.
Ivory said he had an idea early in the week that he would be activated but he wasn't sure until Friday.
"After talking to coach, he wanted to make sure I knew everything as far as what plays I needed to know for this game and just the expectation of what we have going on," Ivory said.
Despite spending the first seven weeks of the season on top of training camp on the PUP list, Ivory said he'll be ready and knows the offense.
Ivory said that though he hasn't been hit or tackled yet, the physical aspect of the game won't take long to get used to, either.
"Actually, after the first hit I'll be OK," Ivory said. "That's all it will take. And with pregame too I'll probably get a couple of thud hits and warm up. But I don't think it's going to take too long to get adjusted to the hits. I know I'll be sore afterwards. It's not going to take much to get adjusted to it."
Tight end David Thomas (concussion) and right tackle Zach Strief (right knee) are questionable after being limited Friday. ... Linebacker Jonathan Vilma (left knee) and defensive tackle Sedrick Ellis (right ankle) were limited in practice and are listed as probable.