Rookie cornerback Casey Hayward has been stellar in nickel and dime packages and will likely have his role expanded with a serious injury to Sam Shields. (US Presswire)

If there’s a silver lining to the serious injuries to CB Sam Shields and OLB Nick Perry, it’s that the Packers have some of their best depth at those positions.

Shields (shin/ankle) and Perry (knee) were ruled out of Sunday’s game at St. Louis by coach Mike McCarthy on Friday. Both players were hurt in last week’s 42-24 win at Houston and neither practiced during the week.

Fortunately for the Packers, they have quality backups behind Shields and Perry.

At CB, Green Bay will likely go with rookie Casey Hayward as the starter opposite Tramon Williams. Hayward has shined in nickel and dime duty, showing off the savvy, instinctive playmaking ability that made him a second-round pick out of Vanderbilt in April. He’s had three interceptions the past two games, including two in the fourth quarter last week against Texans QB Matt Schaub. On the first, he stepped in front of his man and tipped the ball to himself, returning the ball 17 yards. His second interception, which he returned 20 yards, came just after he made a beautiful, textbook knockdown on an end-zone throw, one of his three passes defensed in the game.

“I’m getting a feel for it,” Hayward said. “Whenever the plays come, you’ve got to make the plays, just try to be in the right position.

“I hope I can continue making plays and showing guys around the league what I can do and showing the coaches what I can do, as well.”

The coaches have noticed. And they’ve been impressed.

“I thought he played very well in his opportunities this past weekend with the two interceptions,” McCarthy said, “and I just think he’s a heck of a football player. For a rookie to come in here and play as many positions and to pick it up the way he has, he just needs to play.

“So I’m very happy with the progress he’s making.”

Also encouraging is the fact that second-year CB Davon House was a full participant in practice this week and is listed as probable for Sunday. House, a fourth-round pick out of New Mexico State in 2011, was the early frontrunner to win the No. 2 CB job in training camp. But he dislocated his shoulder in the preseason opener and has since worn a protective harness on the shoulder but hasn’t played yet this season and was only active for games last year as a rookie.

House said Wednesday he’s been ready to go for a few weeks. He’s grown accustomed to the harness and doesn’t think it’ll affect him on the field.

“It shouldn’t be bad,” he said. “I’ve been going full speed in practice, going against A-Rod (QB Aaron Rodgers) and Jordy (Nelson), so that’s helped a lot. My confidence level is really high.”

McCarthy said that House had his best practice of the season Friday and is “definitely close to being ready.”

House could find himself playing in the Packers’ nickel defense, a package they use often, against the Rams. Veteran special teams ace Jarrett Bush is also available.

House was asked to whom the No. 2 cornerback job belonged. He paused for a moment before answering diplomatically and honestly.

“I feel like it’s Sam’s job, and then me or Casey or JB are going to step up and take that spot until Sam comes back and then see what happens,” House said.

“We feel like the difference between our team and other teams is our third- and fourth-stringers can go to other teams and probably start or compete for a starting job,” he said. “So when our guys go down, we’re not really worried about other people stepping up.”

At OLB, it’s a similar situation.

The Packers will play veteran Erik Walden, who was the starter virtually all of last season, at left outside linebacker, opposite Clay Matthews. Walden, who was brought back in the offseason despite concerns about his on-field productivity and an off-field incident, has looked like a different player this year. He’s played with a clear ferocity and intensity not seen before, a pass-rushing force who appears motivated to prove doubters wrong. He’s only registered a half sack, but he’s been close to a few more.

McCarthy said he had no qualms giving Walden, who was splitting time with Perry already, the majority of the snaps at OLB against the Rams.

"Erik Walden has definitely made a step from last year," McCarthy said. "Erik had a chance to go through an offseason program, which he did not (in 2011). I think just the fact going through it from Day One, he's very comfortable in our scheme. I just love the way he plays. Physical. Brings an attitude that you can't have enough of on your football team. He's clearly playing better this year than he did last year.”

Undrafted rookie OLB Dezman Moses, a player the coaches like a lot, could also work into the rotation as a situational pass rusher.

Follow Packers reporter James Carlton on Twitter: @CBSPackers and @jimmycarlton88.