Speedster running back Chris Rainey has shown the Steelers just about everything through 2 1/2 impressive weeks of his first NFL training camp.

But Rainey as a goal-line back? That was new.

The 5-9, 180-pound (and that's generous) rookie from Florida was getting the ball during the popular goal-line drills Sunday at practice.

To be fair, his participation in the drill was more out of necessity and a last-man-standing quality than anything else. Nagging injuries to Isaac Redman and Jonathan Dwyer kept them out of practice, and fellow back John Clay left the workout with a hip/groin injury.

That left Baron Batch and Rainey, who used his blazing speed to score a touchdown during the Steelers preseason loss at Philadelphia Thursday. But that, like most of his touchdowns at the University of Florida, was in the open field. Lining up at the 1 1/2-yard line behind a two-tight end set was different.

"Obviously, he doesn't fit the cookie-cutter of a man who runs in that situation, but he did a nice job today," coach Mike Tomlin said.

"We don't have him in the box, we really don't. He's done just about everything we've asked him to do and we'll continue to find ways and see if he's capable of doing things."

Defense dominates goal-line drills: Out of seven snaps in the practice-ending goal-line drill, the offense scored only once. That was when Rainey extended and crossed the plane -- and the offense never even came close in any of the other snaps. The offense attempted five runs and two passes. Veteran linebacker Larry Foote made two tackles in the backfield.

"From where I stood, it looked like Larry Foote controlled the whole drill," Tomlin said.

Starks predicts he'll be ready in time for opener: LT Max Starks was signed, in part, as insurance for rookie LT Mike Adams. It appears as if the Steelers might need to cash in on that policy. Adams was ineffective at times (especially in pass protection) in the loss to the Eagles, and he left the game with a right knee injury that will keep him out of practice a week or two. Starks' chances of keeping the starting job at left tackle have increased dramatically as a result. Starks said Sunday that he could be ready for the rigors of a regular-season game within three weeks. The team's opener is Sept. 9 -- four weeks from Sunday.

"I feel pretty good," Starks said. "I feel like I'm closer, of course, than I was before I got to camp."

Will Johnson continues to impress: Last week, undrafted first-year fullback Will Johnson already was gaining notice with the way he was carrying the ball and running routes out of the backfield during camp practices. Then, starting hybrid fullback/tight end David Johnson was knocked out for the season with a severe knee injury in a preseason loss at Philadelphia. That has made Will Johnson even more prominent during practice.

Will Johnson had highlights running, catching passes and blocking during drills Sunday.

"I think the more reps I get, the more I can learn and the better off I'll be down the road," Johnson said.

Injury updates: Clay went down in pain and was taken off the field via a cart. The severity of the injury was unknown. ... G Doug Legursky also left practice early due to a strained quadriceps. Tomlin termed him "day-to-day." ... WR Emmanuel Sanders was given the practice off. Sanders was bothered by foot injuries throughout most of last season. ... WR David Gilreath returned to practice after missing Saturday's drills. ... Tomlin said he expected Dwyer and Redman back for Tuesday's practice following the team's off day Monday.

Follow Steelers reporter Chris Adamski on Twitter @CBSSportsNFLPIT and @BuzzsawPGH.