That thin air in Denver just got a little thinner for the Steelers' defense with the news that Travis Kirschke almost surely will not play Monday night, and he could miss more time.

Bring on the oxygen, along with rookies Ziggy Hood and Sunny Harris. Those two -- Hood has played sparingly and Harris not at all -- will play more prominent roles in Denver.

Nick Eason will replace Kirschke, who replaced Aaron Smith as the starting left defensive end. Brett Keisel starts at right defensive end. Hood and Harris are the only other ends on their roster. Harris, of course, was not on their roster until two weeks ago because they cut him, Carolina claimed him and they got him back when the Panthers released him.

The Steelers and their longtime defensive line coach John Mitchell have often spelled their starting three with backups, and they have done it more often in the high altitude of Denver.

"We've played there a few times and we know what it's like," said veteran backup nose tackle Chris Hoke. "I played in high altitude in college, so you need to make sure you have a good rotation going."

Hoke will rotate with Casey Hampton in the middle, but he also could be called on to take a few snaps at end. He has practiced there in the past and expects to take some snaps at end in practice this week.

Kirschke does not expect to play because of a torn left calf muscle, which normally requires three to six weeks to recover "typically when you have a tear on your calf," Kirschke said.

It will be two weeks Sunday since the injury forced him out of the game against Minnesota.

"They're happy -- from what they see on the MRI, the type of tear and how much -- that it will be quicker rather than longer," Kirschke said of his return. "I'm preparing myself as if I am playing. However, the injury I have usually takes a little longer than a few weeks."

That means that Hood, picked in the first round, and Harris, picked in the sixth, should see plenty of playing time in Denver. There is no getting away from rotating the defensive line. Hoke, in his ninth season with the Steelers, also played at Brigham Young.

"You're not worried about it in the first and second quarter, you're worried about it in the third and fourth quarter. You may think in the first quarter, hey, I'm going strong. Come the fourth quarter, though, you probably wish you had a few less snaps."

Kirschke, who lives near Denver, concurs.

"I think we'll be OK, but the key will be to rotate early and often, so you don't get to where you need it badly at the end."

Denver has not been kind to that Steelers' defensive line, either. That is where Aaron Smith's 2007 season ended with a torn biceps, which left the Steelers with only three healthy defensive ends in that 31-28 loss.

"We went out there, and Aaron Smith got hurt," Eason recalled. "I was getting 10-15 snaps a game, and he went down and I got about 40. It was me, Travis and Keisel.

"It wasn't a huge issue, I wasn't about to die or anything. I did some oxygen, of course. I'm going to have plenty of oxygen."

Hood had practiced strictly on the left side this year, but believes he will take a few snaps on the right side as well. Harris has played on the right since rejoining the Steelers.

Keep the oxygen and the rookies coming.

"Get the starters out," Hood said of his role Monday night, "so they can catch their breath and they can be 100 percent every snap."
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