James Harrison would not classify his latest issue with his knee as a setback, even though the Pro Bowl outside linebacker is not expected to play Sunday night in Denver.
Harrison did not practice for the second day in a row Friday and is listed as questionable on the team's official injury report.
He will be replaced in the starting lineup by Chris Carter, who has been working at right outside linebacker since minicamp because of injuries to Harrison (knee) and top backup Jason Worilds (wrist).
This is the third time since spring that Harrison has had a comeback halted by a knee problem. In his other attempts -- once at minicamp, once at training camp -- his knee swelled each time he tried to cut on it.
Harrison said Friday he did not suffer a setback this time, nor is he worried about his knee.
"No, it's just sore," Harrison said. "The soft tissue just hasn't healed up."
Harrison returned to practice Monday for the first time since last season. The plan was for him to get enough reps to be able to start against the Broncos, provided he didn't have any problems with his knee. It is not known if the latest problem will cause Harrison to miss as much time as he did in the spring and summer.
"If the game were today, I couldn't play," Harrison said in a response to a question.
In addition to Harrison, running back Baron Batch also was listed as questionable, although he practiced Friday. Running back Rashard Mendenhall (knee) was listed as doubtful. Inside linebacker Stevenson Sylvester and safety Ryan Clark were ruled out.
The Steelers did not waste any more time and placed rookie guard David DeCastro on the new injured reserve/designated to return list that allows him to come back after eight games.
Only one player per team can be designated for the list. DeCastro is allowed to resume practicing after six weeks and is eligible to come off the IR list in eight, although his recovery from a knee injury might be longer than that.
The Steelers made the move to make room on the 53-man roster for cornerback DeMarcus Van Dyke, who was signed after being released by the Oakland Raiders. Van Dyke is in his second year from Miami.
The Steelers did not appoint a special teams captain when they named Ben Roethlisberger (offense) and Brett Keisel (defense) as team captains for the 2012 season.
Instead, Tomlin will appoint a different special teams captain each week to go out for the coin toss. Veteran safety Will Allen could be the leading candidate to handle the duties in Denver.
Denver rookie defensive end Derek Wolfe already has worked himself into the starting lineup, and that is no surprise to the Steelers.
They spent a lot of time talking with the 6-foot-5, 300-pound lineman from Cincinnati at the scouting combine in Indianapolis and considered taking him high in the NFL draft.
But the Broncos beat them to it and took Wolfe in the second round. He plays at right end in their 4-3 alignment but slides inside in their sub packages.
Wolfe combines with defensive end Elvis Dumervil and linebacker Von Miller to give the Broncos three good pass rushers in the front seven.
"You have two of the premier [pass] rushers in the league, and they drafted a young guy in Wolfe," said offensive coordinator Todd Haley, who faced the Broncos twice a year when he was head coach in Kansas City. "They have active, physical guys who play hard."