Here’s a rundown of what to watch for in this first game.

Morgan Burnett’s debut
The rookie third-round draft pick was expected to be in a heated battle with safety Atari Bigby for a starting job, but Bigby’s ankle injury and subsequent surgery have plunked Burnett right into the starting lineup from the get-go.

With Bigby absent without a signed contract all offseason, Burnett was working with the No. 1 defense all through OTAs and the mandatory mini-camp in June, and then picked up where he left off in training camp. He’s had a couple of interceptions in team and 7-on-7 work in camp, but his primary focus has been getting the playbook and his communication responsibilities down.

“It’s like any rookie,” defensive coordinator Dom Capers said. “He hasn’t seen the number of snaps other guys have. Every time he sees something that will be the first time.

“It will be interesting to see how he adapts to playing against an opponent where things aren’t scripted, that he has to react based off of what they do. Obviously in these preseason games, you could see a lot that you haven’t prepared for.”

Young cornerbacks
Speaking of the secondary, the battle for the nickel cornerback spot behind current starters Charles Woodson and Tramon Williams begins in earnest between second-year pro Brandon Underwood and third-year man Pat Lee. Williams will start opposite Woodson until Al Harris returns from his knee injury, so one of the young guys will have to be the nickel. And when Harris returns, the dime.

Underwood has been taking the first nickel snaps in camp thus far, but Lee has been rotating in. Underwood has talked about feeling much more comfortable with and knowledgeable about the defense compared to his rookie season, while Lee is fully healthy after two injury-riddled years to begin his career.

“Coming into camp, we knew those were going to be two key guys for us,” Capers said. “So our plan has been to try to get them as many repetitions out here and get them as much playing time as we can in these preseason games.

“They’re important for our defense. They’re two young guys that we think have talent. We like their size. I think they’re both pretty smart guys. For our sub packages, they’re going to factor significantly, both of them.”

Don’t overlook non-drafted rookie Sam Shields either. He’s made several standout plays in camp so far, including a 100-yard interception return in last Saturday’s scrimmage and an impressive one-handed snag for a pick along the sideline in Thursday’s practice, when he made a perfect break on an out route.

It will still take a lot for the raw, speedy Shields to surpass Underwood and Lee on the depth chart, but it’s impossible not to like what’s been seen so far.

Backup quarterback Matt Flynn
Preseason is the most important time for Flynn to continue his development, and he’s eager to take the field after a shoulder injury limited him to just eight pass attempts in the preseason a year ago.

With the starting offense expected to play only a couple of series, Flynn should get a lot of snaps against the Browns. He gained some valuable playing time at the end of the regular season last year when Rodgers rested, experiencing both positives (two scoring drives vs. Seattle) and negatives (an interception at Arizona).

“I’m excited,” Flynn said. “I’m excited about the group of guys we have on the No. 2 offense. It’s going to be fun to go out there, put what we’ve done in practice into a game, and go out there and execute and produce.”

The No. 5 wide receiver competition
Brett Swain won this job last year because of the combination of his receiving and special- teams abilities, and it will take similar versatility to get the spot again this season. So while it’s worth watching which receivers make some plays with Flynn and No. 3 QB Graham Harrell in there, keep an eye on the punt and kickoff coverage teams too.

“Brett is kind of the guy people are gunning at, and the special teams aspect of that is huge,” receivers coach Jimmy Robinson said.

Swain has missed some practice time coming off ACL surgery and due to a scare with his knee in last Saturday’s scrimmage, but he’s still the favorite to keep his job. Of the others in the mix – Charles Dillon, Chastin West, Patrick Williams, Jason Chery and Shawn Gore – it’s been hard not to notice Dillon. He has had a lot of passes thrown his way in camp and has caught the eye of special teams coordinator Shawn Slocum on the coverage units. In 2009, Dillon played Arena football, where players go both ways, so his tackling skills come in handy on special teams.

“I think it’s a pretty tight competition,” Robinson said.

The punting battle
The practice punts of Tim Masthay and Chris Bryan have been tracked and charted, ad nauseum. But it’s been clear from the beginning that this competition will come down to preseason game performances.

Head Coach Mike McCarthy said he’s planning to split the game duties as evenly as possible, though he hasn’t decided if Masthay and Bryan will trade off every punt or every two. As for the holding duties, one of them will be the holder for the entire game, with the other one holding the next game.