Safety Aaron Rouse hadn't played since the first preseason game when he was thrown into action in the season opener last Sunday night, first for Nick Collins when he left the game with cramps, and later for Atari Bigby after he went out with a knee injury.

Unfazed by the long layoff, Rouse held his own as a fill-in, and now suddenly he's staring at full-time duty for perhaps a month or more, with Bigby's injury projected to keep him out at least four weeks.

"Hopefully (Sunday) night will be a good indication of what we're going to get, because he did a good job of coming in and picking up right where Atari left off," safeties coach Darren Perry said. "We tell our guys that you're only one play away, sometimes two plays away, from having two (new) guys in there, because it can happen that quickly.

"That's just a credit to him in terms of preparing and being ready to accept that challenge. That if something were to happen, that he could go in and be a guy we could count on. We're going to have to count on him even more now, and the expectations are high. He understands that, and this is a great opportunity for him."

Rouse, who had injured his hamstring back on Aug. 20 and missed the final three preseason games, was credited with three solo tackles in his spot duty against the Bears, including a crunching hit on Chicago's Desmond Clark that knocked the tight end out of the game.

Both Perry and Rouse himself credited the extensive studying of the new 3-4 scheme during spring workouts and organized team activities (OTAs) for his ability to step right in and play for the first time in a month.

Rouse got extensive work as the No. 1 free safety during the spring while Nick Collins was absent, a position that Perry refers to as the "quarterback" of the defense. According to Perry, Rouse "took the bull by the horns" and was getting everyone aligned properly and making all the checks and calls before the snap.

So even though he'll now be playing Bigby's spot and not Collins', he's more than mentally prepared to play in this defense even if the physical reps were limited by the hamstring injury.

"To get in early and learn the scheme, it definitely helps you out tremendously," Rouse said of diving into his playbook in the spring. "Being a safety and one of the major communicators out there in this defense, you have to know what's going on, you have to know what parts are working and how everything works. I made sure it was a priority for me to get back early in the offseason and learn this defense."

Stepping into the starting lineup is nothing new for Rouse, a 2007 third-round draft choice out of Virginia Tech now in his third season. He started three consecutive games as a rookie in 2007 when Collins went down with a knee injury, and he recorded his first two career interceptions.

Then last year, he started a total of six games for Bigby as well as finished a couple of games the oft-injured Bigby couldn't. He recorded two more interceptions, including a Lambeau Field record 99-yard interception return for a touchdown against the Indianapolis Colts and Peyton Manning.

But Rouse has had his share of struggles too, which is partly why he hasn't gotten stronger consideration to be a full-time starter. He's been caught in the wrong alignment at times or taken poor angles in coverage or as a tackler.

Perry, who is coaching Rouse for the first time, believes that's just part of the process of growing into the position at the pro level and balancing all the responsibilities that come with it.

"To be a great safety you have to have good vision," Perry said. "When he came out of Tech, he was near the line of scrimmage, and he was like an outside linebacker. Now you put a guy 14, 15 yards back deep and ask him to see the whole field, feel routes, not let anybody get behind you, but at the same time be able to pattern read and get close to routes, it takes some time.

"But he's made tremendous strides, and I'm looking for him to continue growing."

Perry noted there were a couple of plays against Chicago where, with a better feel for the entire field, Rouse could have tightened down his coverage. Those are the types of plays he'll look to improve on.

Part of that will come with confidence, Perry said, and part of it is physical technique. At 6-foot-4 and 227 pounds, Rouse is very big for a safety, and his height can hinder the quick-twitch change of direction needed sometimes.

{sportsad300}Perry has been working with him on improving his knee bend and his pad level, which should improve his reactions and explosion to the ball. The hit on Clark was an example of the downhill burst a safety needs to try to break up a play, even though Clark made a nice catch and hung onto the ball.

"He's doing a good job with it in terms of paying attention to detail," Perry said. "We would have liked to see more snaps out of him during the preseason to feel comfortable about it, because it's one thing to do it in shorts, but to do it in pads is another.

"So you're still kind of hoping a little bit, but (Sunday) night is a good indication of where we think we can go with him as a player. He's just got to understand that and keep going forward."

For his part, Rouse says he's ready and he's feeling no lingering effects from the hamstring problem. The defense he spent so much time learning and studying "allows you to have fun," he said, but at the same time he's taking the same disciplined approach to preparing for Cincinnati on Sunday that he did to learning the new defense back in the spring.

"Most definitely I'm excited, but I think that excitement has to come in measurements," he said. "What I mean by that is you have to stay focused. You can't go out there and be too wild or wide-eyed. You have to take your time, be focused and play your part. Know your role on the team.

"I'm extremely focused this week."