During OTAs over the past month, young players like Pat Lee and Brandon Underwood, along with veteran Jarrett Bush, have taken the vast majority of first-team reps at cornerback, as have veteran Pro Bowler Nick Collins and rookie third-round draft choice Morgan Burnett at safety.

That has left the second and third units to be filled out by a slew of rookies and other young players trying to make their mark. The OTAs have provided a significant opportunity for cornerbacks Josh Bell, Trevor Ford, D.J. Clark and Sam Shields, along with safeties Charlie Peprah, Anthony Levine and Khalil Jones, to get noticed.

But that depth chart is almost certain to change, and perhaps dramatically so. The list of defensive backs who have been absent from OTAs for various reasons includes some major contributors at those positions, many of whom will be counted on once again to play notable roles on defense.

Cornerback Tramon Williams and safety Atari Bigby have restricted free agent tender offers pending from the club, while three others - cornerback Al Harris, safety Derrick Martin and former corner turned safety Will Blackmon - are coming back from injuries. (Woodson has been with the team throughout much of the OTAs but has practiced sparingly to rest up for the season.)

The picture could be altered as soon as next week at the mandatory mini-camp if Williams and/or Bigby sign their tenders. None of the injured players are expected to participate next week, but Martin and Blackmon are both on track to return for training camp, while Harris' timetable remains uncertain.

What's developing is a situation where the intensity of the competition during training camp, both for starting spots in the case of Burnett and Bigby and roster spots in general for the others, could be more heated in the defensive backfield than at any other position, as the veterans' experience from past seasons meets head-on with the youngsters' opportunities to progress from this spring.

"I really like the depth and I'm very happy with everyone that's been out there working," Head Coach Mike McCarthy said, specifically referring to the safeties, which he called the deepest group in his five seasons as head coach. "That's going to be a very competitive position come training camp. And I would really say the same thing for corner."

How the competitions play out when the pads are strapped on later this summer and the real hitting begins will be watched closely. It's common in NFL circles for players to look like potential contributors in shorts and helmets during non-contact work, only to see that potential never come to fruition in full pads.

While no one disputes that Woodson, Harris (when healthy) and Williams (assuming he signs) are the team's top three cornerbacks, the Packers are obviously interested in developing their depth after seeing the position ravaged by injuries last year.

McCarthy has mentioned several times how much Lee, who has lost much of his first two seasons to injuries, and Underwood, a sixth-round draft pick a year ago, have benefited from the first-team reps, while Bush has gotten to focus strictly on corner rather than rotate between corner and safety as he's done in the past.

Shields is the newest member of the group, having signed as a rookie free agent following the draft and beginning a full-time conversion from receiver to cornerback. Meanwhile, Ford, Bell and Clark were all here for the entire offseason program, and though they have minimal if any game experience -- Bell has the most, having played for both Denver and Green Bay the past two seasons -- they've gotten more reps in team (11-on-11) drills over the past month than most in their situation.

"I think all of our younger guys, the quality of work, the volume of work that they've had since March has really helped them," McCarthy said. "I think it's evident on the practice field."

The same holds true at safety, where Burnett continues to receive rave reviews working with the No. 1 defense in Bigby's absence. His reputation as a 'ball hawk' at Georgia Tech, where he intercepted 14 passes in just three seasons, has shown up during workouts all month.

McCarthy commented that "things come very easy for him," and while that's not necessarily true in Burnett's eyes, he does feel light years ahead of where he was during rookie mini-camp in early May.

"I'm starting to get a little comfortable back there, starting to pick up the defense a little more," he said. "But I'm still learning and trying my best to learn as quickly as I can."

The return of a fully healthy Bigby could make for one of the most-watched training camp battles this summer. The reserve safety spots will be up-for-grabs too, as Blackmon returns from his knee injury and adjusts to his new position, while Martin gets to work from the beginning of camp rather than at the end, when he arrived in a trade with Baltimore last year.

Earlier this offseason, Martin had surgery to clean up the badly sprained ankle that kept him out of the Packers' playoff game in January. He had to stay off the ankle completely for about six weeks and has now begun some jogging and light running.

He expects to ramp up his workouts soon and be close to full strength early next month, leaving him plenty of time to hit the ground running for the first training camp practice on July 31.

"It's always hard when everybody else is working and you're not working," Martin said. "But they're out there looking good, so that's a good point. When everybody is flying around, (the defense) looks good, so as long as they keep doing what they're doing, I'll be ready when the time comes."

Everybody in the defensive backfield had better be, especially if the whole group is finally on the field together for training camp.