By Jason Wilde
Channel3000.com's Packer Insider from ESPN Madison

GREEN BAY -- Sam Shields may not get another opportunity to catch and return a kick anytime soon.

But the Green Bay Packers undrafted rookie free agent will get a colossal opportunity Thursday night against Indianapolis at Lambeau Field to prove he not only belongs on the 53-man roster but also could be a contributor this season.

Shields’ follies as a returner – general manager Ted Thompson called them “gaffes” on Tuesday, which qualifies as public criticism coming from him – have been glaring in the first two preseason games:

Against Cleveland, he bobbled a kickoff before downing it for a touchback, then muffed and lost a punt; and against Seattle on Saturday night, he could neither field nor recover a short kickoff, allowing the Seahawks to recover and giving him two special-teams turnovers in as many weeks.

But those two hard-to-miss mistakes have clouded the truth about Shields: That he’s not only an excellent bet to make the team, but that he could be playing a key role in the Sept. 12 regular-season opener at Philadelphia.

On defense, Shields will work with the No. 1 nickel group against the Colts, meaning he’ll line up as the third cornerback along with reigning NFL Defensive Player of the Year Charles Woodson and fellow starter Tramon Williams in passing situations.

Until now, second-year man Brandon Underwood had held a slight edge over third-year man Pat Lee for that No. 3 cornerback job. Now, Shields has barged into the conversation, according to both cornerbacks coach Joe Whitt and defensive coordinator Dom Capers.

“We just think we’ve got to give him a chance to show what he can do,” Capers said. “You see his quickness and his explosiveness, which is something that if a corner has that and he can then learn the techniques, you normally see them progress because they have the type of physical tools that you’re looking for in terms of being able to close and make plays on the ball.”

The coaches now need to see what Shields can do against better competition – namely, Peyton Manning and his wide receiving corps – because he’s been terrific playing with the second and third units. In the team’s loss to Cleveland Aug. 14, he was in perfect coverage and dropped an interception that would have likely sealed a Packers victory; against Seattle on Saturday night, he picked off a Charlie Whitehurst pass with 2:50 left in the game to preserve their 27-24 triumph.

“He’s shown that he’s had the ability to make plays, get his hands on balls,” Whitt said. “He’s shown the ability to cover, they haven’t completed balls on him, but at the same time, he’s not going against their (No.) 1 receivers, their (No. 1) quarterback. The ball’s coming out slower and the receivers’ routes are slower. So I’m going to give him the opportunity to go against these fast guys, the best quarterback in the league, and see what he does with that.”

What’s remarkable about Shields’ play at cornerback is that he only spent one year at the position in college at the University of Miami (Fla.). While his remarkable speed (a 4.2-second 40-yard dash) made him an intriguing prospect, his inexperience made him a long shot to have an impact there.

“It didn’t take long to see his talent; it’s just a matter of the number of things that he hasn’t seen at the position,” Capers said. “He’s worked very hard. It’ll be interesting to see how he does Thursday night. This will be a good test for him.

“Once we start playing these games in a couple weeks, your evaluation is going to be based on them going against the best. And sometimes you can get a little false sense of security if you don’t have an opportunity to do that. The more we can see those guys against the No. 1s that they’re going to be playing against, it gives us a truer evaluation of where we are.”

The No. 3 cornerback job is a vital position because the Packers play roughly 50 percent of their defensive snaps in a sub package (either nickel or dime), and because two-time Pro Bowl cornerback Al Harris may not be ready to start the season. Harris, who suffered a career-threatening knee injury last November, had hoped to begin practicing this week but failed to get the go-ahead from the medical staff.

“He is getting better and better. All of the reports are always positive when we talk to medical staff,” coach Mike McCarthy said. “But there is a protocol when you come off a major injury that Al has gone through. He is doing everything he can, I can promise you that, but still today he is not ready to pass the physical.”

As a result, the young cornerbacks have gotten extensive work – not that Whitt wouldn’t rather have Harris in the mix right now.

“There is no silver lining to not having Al Harris. If you add him to our secondary, we’re by far the best secondary in the NFL,” Whitt said. “(With) him, Charles Woodson, Nick Collins (and) Tramon, that’s as good as you’re going to get. And when you take that type of player away, you’re just not as good. (But) just because he’s not here, we’re not going to change our standard of play.”

And so far, Lee and Underwood have not played to that standard. Underwood, who had been the frontrunner for the job, played poorly against Seattle, and both players have struggled to take solid performances at practice and carry them into game action.

“We’ve practiced well, (but) we haven’t really translated it to the games. We have to play better,” Whitt said.

Meanwhile, it won’t just be a big night for Shields on defense. Special teams coordinator Shawn Slocum has put him with the No. 1s on three of the four core special teams units: Kickoff coverage, punt coverage, and punt return.

“He’s a dynamic athlete. I think you can see his speed; it’s evident that’s unique,” Slocum said of the 5-foot-11, 184-pound Shields. “He’s got good durability, he’s tough, he’s smart, he is willing to work hard. We’re going to put him in a position special-teams wise to make some plays this week, and I want to see him play and play well.”

What Shields won’t be doing is catching punts or kickoffs after his adventures in the first two weeks. His value now is as a gunner on the punt coverage team, in the No. 2 spot on kickoff coverage and out wide on punt returns – where his speed is a difference-maker.

“We threw him in the fire, and he had a couple problems,” Slocum admitted. “But as I told him, ‘Keep your head up, man. There’s a lot of opportunity on this football team. I think he can be an asset.”

Despite the turnovers, Shields doesn’t seem overwhelmed by anything so far. When Thompson said Tuesday that the game “doesn’t look too big for him,” he was right. And Shields intends to keep proving that.

“When you get your opportunities, you have to make things happen, make a big play out there,” Shields said. “I’m so much more comfortable now (at cornerback). Just working with some of the veteran guys and staying in my playbook, it’s helping me out a lot. Every day on the practice field I get more comfortable and more comfortable, and more confidence.”