To put it mildly, the Green Bay Packers' defensive backfield is in a state of flux right now, but Head Coach Mike McCarthy believes the unit has the depth to make the necessary adjustments, both at cornerback and safety.

For starters, Tramon Williams will be stepping in at cornerback in place of Al Harris. Fortunately, the news Wednesday wasn't all doom and gloom for Harris, who sustained a serious injury to his spleen in Sunday night's game against the Cowboys.

Harris and the medical staff are still in the process of getting additional opinions on his spleen injury, and McCarthy said once all the information is gathered, a timetable will be set for his treatment and recovery. This week Harris can do nothing but rest, but it's possible surgery won't be necessary. And while noting the seriousness of an internal injury, McCarthy didn't rule out the chance that Harris could still return to the field in 2008.

"If Al was standing here, he'd tell you he wants to play this week," McCarthy said. "That's kind of how he feels. But once again, ... it's a different type of injury, and we're getting as much information as possible. I'm hopeful that he'll be back. The time frame just hasn't been established yet."

However long Harris may be out, Williams feels he's prepared to fill in. The second-year cornerback has gone from a practice squad addition late in 2006, to buried on the depth chart at the start of training camp in 2007, to a surprise inclusion on the 53-man roster, to the nickelback for last year's playoffs.

His rise has been as impressive as it is stunning, and now the former walk-on at Louisiana Tech will be an NFL starter for at least a handful of games.

"You know how long a road it's been, but it's a big opportunity," Williams said. "I'm looking forward to it, preparing real hard for it. Preparing like I've been preparing of course, but really preparing for it."

For a young player with just one NFL start to his credit (he started the regular-season finale last year when Charles Woodson was resting up for the playoffs), Williams has a fair bit of experience. He played in every game a year ago, alternating between the nickel and dime spots and posting 11 tackles (10 solo) with one interception and four passes defensed.

Like any young cornerback, Williams has had his ups and downs. Just last week against Dallas, he made a nice break-up of a deep pass over the middle to Miles Austin, only to be beaten by Austin later on the same drive for a 52-yard touchdown when Austin outjumped him for the ball.

But he also has the short memory necessary to play the position, and he has the confidence of his teammates and coaches behind him.

"I'm happy for him, I know he's ready," said fellow cornerback and good friend Will Blackmon, who is now the top candidate to move up to Williams' old nickel slot. "He's not worried about anything. Everybody has their bumps, that's part of the game, and you learn from what happens."

Added McCarthy: "He's a true testament to hard work, the offseason program. He had a good year last year, and we feel very comfortable letting him step in there and play. I'm excited for him, and we won't even blink with him in there."

The Packers are hoping for the same thing at safety despite some uncertainty. Atari Bigby (hamstring) did not participate in practice on Wednesday and could miss his second straight game, while Nick Collins (bruised back) was limited in practice.

Collins was doing more than just standing around during the jog-through portion of practice open to reporters, so that's a good sign for his potential availability. But Bigby's replacement last week, second-year pro Aaron Rouse, was also limited in practice due to a knee injury and his status is undetermined at this point.

{sportsad300}No matter how the week unfolds, No. 4 safety Charlie Peprah and converted cornerback Jarrett Bush will need to be ready at safety, while Bush and rookie Pat Lee, who has been inactive the first three games, may be needed at corner in the dime defense.

"They will all take reps in those positions this week," McCarthy said. "I like the depth there. I like the depth of our safety positions. I feel we have four very good players there, and Jarrett Bush is natural back there frankly. We're going to rotate all of those guys in and make sure they are ready."

But regardless of the lineup that emerges, no one will have the spotlight on him any brighter than Williams. As a nickelback behind Harris and Woodson, Williams has grown accustomed to getting picked on by opposing offenses, but that only becomes more magnified now that he'll be on the field virtually every snap on defense.

Williams certainly expects the Buccaneers to attack him this Sunday, but he has no plans to back down.

"A new guy, you've got Charles Woodson on the other side, why not?" he said. "But we'll see what's going to happen.

"At one point I didn't think experience mattered that much, but it really does matter, and I'm glad I've got that under my belt. I'm just ready to go out there and show it."