As many as six offensive rookies, including two undrafted free agents, could make the final 53-man roster, and one of the biggest surprises is tight end David Johnson, a seventh-round draft choice from Arkansas State.

Johnson (6-2, 260) first caught the coaches' attention early in training camp when he was matched in a blocking drill against Pro Bowl linebacker James Harrison, the NFL's defensive player of the year. And he hasn't stopped there, excelling in drills against other linebackers and defensive ends.

"He's the first guy I've ever seen knock James Harrison an inch backward," said offensive coordinator Bruce Arians. "Not a foot, but an inch, anyway.

"He's just so powerful when we put him up against linebackers. And against our defensive ends, he really stood out. You talk to those guys, they say, 'Man, this kid's got some punch.' And he can run and catch."

Johnson is competing for the third tight-end spot with veteran Sean McHugh, who also lines in the backfield as an H-back/fullback. McHugh signed a three-year contract in the offseason, but he could be pushed out of his role by Johnson.

"If he continues to come around, we might have found a jewel because that's the guy who can also play fullback," Arians said.

The other offensive rookies who could make the final roster are wide receiver Mike Wallace, guard Kraig Urbik, guard/tackle Ramon Foster and running backs Isaac Redman and Frank Summers. Foster and Redman are undrafted free agents.

Harrison did not practice yesterday because of a stomach virus. "We chose to leave him inside," coach Mike Tomlin said. Defensive end Nick Eason (calf) missed his second day in a row.

Summers injured his hamstring, and Tomlin said he doesn't know the extent of the injury. Cornerback Anthony Madison was excused for a third day because of a death in his family.

It wasn't a coincidence that Tomlin put 2 minutes, 37 seconds on the clock and the ball on the 18-yard line to practice the two-minute drill.

That was almost the same situation in Super Bowl XLIII when Ben Roethlisberger moved the Steelers 78 yards in eight plays to produce the winning touchdown to Santonio Holmes with 35 seconds remaining.

Technically, the Steelers began the winning drive at their 22 with 2:30 remaining, but a holding penalty against guard Chris Kemoeatu on first down moved the ball back to the 12.

"We executed some two-minute football," Tomlin said. "We saw some good things, on both sides."

The Steelers will have their final practice that is open to the public at 3 p.m. today before breaking camp, and maybe no other player is happier to leave Saint Vincent College than nose tackle Casey Hampton.

He said he can't wait to sleep in his own bed at night.

"Everybody knows I don't like camp," Hampton said. "It's something you got to do and you got to push through it."

This has been a different training camp for Hampton, 31, unlike last year when he reported nearly 40 pounds overweight and was placed on the physically-unable-to-perform list for two weeks. He spent most of his time at training camp riding a stationary bike and jogging around the practice field.

"All camps are the same -- I dread coming here," Hampton said. "I just try to get through it and on to the season."

Is there anything he will miss?

"No," Hampton said.

The camaraderie?

"No," he said. "I don't want to see these guys at nighttime."

Defensive end Ziggy Hood, the team's No. 1 draft choice, has been playing behind Aaron Smith on the left side of the defensive line. But, he lined on the right side in the team's nickel and dime packages in the preseason opener against Arizona and registered his only sack from that side.

When Hood lined on the right side, he stood like a linebacker and did not put his hand on the ground, like he does on the left side.

"I just try to mimic Brett Keisel -- whatever he does, I try to do," Hood said. "It's really not anything I prefer. Whatever they do, I just try to do."

Hood said defensive line coach John Mitchell cautioned him about trying to emulate Keisel too much.

"Brett is good at what he does, and it took him some years to do that," Hood said. "I'm just trying to catch on real fast and learn what he does and just try to model myself after him because he's a great player."