With the third preseason game considered the most realistic "dress rehearsal" for the regular season, the Green Bay Packers would be hard-pressed to find a tougher opponent than the one they're facing Friday night.

The Arizona Cardinals are the defending NFC champions who came within one final Pittsburgh Steelers drive of winning Super Bowl XLIII last February in Tampa. But if you're going to play a game as close to a real one as possible in the preseason, you might as well take on the team everybody in the NFC will be trying to knock off come September.

"This is a great opportunity to play this football team and to play them on their home turf," Head Coach Mike McCarthy said. "This will be a big test for us. We have questions we're still trying to work through and making sure we have our personnel groups ready to go as we move into the regular season, but this is a big opportunity for us."

On both sides of the ball. The Green Bay offense, which has scored five touchdowns in six possessions thus far in the preseason, will face an Arizona defense loaded with experience in the front seven and featuring legitimate playmakers in the secondary in safety Adrian Wilson and cornerback Dominique Rodgers-Cromartie. The Cardinals' 3-4 scheme doesn't function exactly the same as the Packers', but Green Bay's extensive work against defensive coordinator Dom Capers' 3-4 alignment should help.

"It will be a good test for us on offense to try to move the ball on an experienced defense like that," quarterback Aaron Rodgers said. "It's a different philosophy, what Dom does compared to what they're doing on defense."

Meanwhile, Arizona's offense features two-time league MVP Kurt Warner at quarterback, along with one of the most explosive receiving corps in football, with Larry Fitzgerald, Anquan Boldin and Steve Breaston, all of whom topped 1,000 yards a year ago.

"Obviously they went to the Super Bowl last year, and they didn't get there for no reason at all," linebacker Nick Barnett said. "It will be a good challenge for us to see exactly where we are."

This will be the second preseason opponent the Packers are scheduled to play in the regular season. The rematch of the preseason opener against the Browns will be on Oct. 25 in Cleveland, while the Packers and Cardinals will see each other again in Arizona in the regular-season finale, Jan. 3.

"I think it's an interesting game because we play them later in the season, so I'm not sure how much both sides are going to show each other, although that will be after 15 games played," Rodgers said. "But it will be interesting to see how they play."

Knocking it around

Barnett was back to full participation in practice on Monday, but Tuesday was his first full-contact work in pads and everything appeared to go smoothly.

"I don't feel any limitations at this point," said Barnett, coming back from his 2008 ACL surgery. "I feel fast, feel like I can push off of it, feel like I can hit. We'll just take it day by day and learn about it as we keep going. I feel pretty good."

Barnett said he feels little "pops" in his knee on occasion, but the doctors have told him that's just scar tissue breaking up and it's nothing to worry about. He's been told the surgically repaired knee won't feel the same as the other one for a while, but a long, physical practice like Tuesday's - the players worked out for roughly 2½ hours in full pads - helps to get past some of those mental hurdles.

"I did a lot of cutting out there, did some hitting, a little bit of pushing," he said. "I did everything I need to do, covering tight ends, backs out of backfield. The only test now is endurance and we put it through a lot of work today. So we're going to see how it feels tonight.

"I thought I was going to be exhausted today, and I felt great, honestly."

Barnett feels he's in tremendous shape, thanks to the extensive rehab work he did the entire offseason. He wasn't able to participate in any of the OTAs or mini-camp practices in June, but he continued to rehab vigorously and says his latest body scan shows 10 percent body fat, the lowest it's ever been.

Potentially playing this Friday night remains up in the air, though.

"I don't know, that's on them," Barnett said, referring to the team's medical and coaching staffs. "We'll take it one step at a time. I practiced a lot today. If they want to see me out there for a couple of plays, I don't have a problem going out there. I think it would be pretty fun. But it's on them. I'll let them make the decision when time comes."

Emergency duty

With backup quarterback Matt Flynn (shoulder) and punter Durant Brooks (hip) out of action, wide receiver Ruvell Martin was the holder for kicker Mason Crosby's field goals in practice on Tuesday.

Martin is listed as the No. 3 holder on the depth chart and has been a backup holder in his first three seasons with the Packers. Last year, when punter and No. 1 holder Jon Ryan was released at the end of training camp, Martin may have become the regular holder if not for a broken finger that hampered his ability to handle the ball. Instead, the duty went to punter Derrick Frost, with Flynn backing him up, and then to Flynn when Frost was released after 12 games.

Martin held for an extended sequence of field-goal tries during Tuesday's practice without incident. He last worked as a regular holder in college at Saginaw Valley State, and he could be called upon for that duty on Friday night in Arizona, though Flynn hasn't been ruled out.

"I love it," he said. "I enjoy doing it, just being part of something else in the game, having the kicker depend on you to make sure you get your job done. It's fun to me."

On the mend again

When Justin Harrell's bad back flared up on him again a couple of weeks ago, the third-year defensive lineman feared the worst. But Harrell said the prognosis for now is that he won't need another surgery and he's looking to return to the field as soon as his back pain becomes manageable.

{sportsad300}When that will be is impossible to say at this point, with Harrell's back troubles having begun in the spring of 2008. They manifested themselves as a hip problem late last season, and his lower back became the issue once again this training camp.

"It's doing better," said Harrell, who is taking medication and said injections are a future possibility. "We're trying to progress and do a little more each day, and when it starts feeling good, they're going to let me go."

Harrell said he may just have to learn to deal with flare-ups as long as he's playing football, but through consulting with several doctors he has learned more and more about the problem and feels he'll eventually be able to manage it.

"I'm doing a lot better this week than I was last week, so that's encouraging," he said.

Injury/participation update

New to the injury list on Tuesday was linebacker Desmond Bishop, who was very limited in practice because of a bruised toe.

In addition to Flynn, Brooks and Harrell, remaining out were cornerbacks Will Blackmon (quad) and Pat Lee (back), safeties Charlie Peprah (knee) and Aaron Rouse (hamstring) and linebacker Clay Matthews (hamstring).

McCarthy said linebacker Jeremy Thompson, who is back this week from a shoulder stinger, was scheduled to practice all week and should see his first game action on Friday. Flynn could be close to returning to practice on Wednesday and hasn't been ruled out of the game.