DENVER — Given the attention paid to the Green Bay Packers' inconsistency on offense during the first two preseason games, the first-string defense's shortcomings had largely gone unnoticed.

Until Friday night's 27-24 victory over the Denver Broncos at Invesco Field, that is.

The Packers' No. 1 defense allowed a dispiriting 99-yard second-quarter drive and let the Broncos score on each of their three first-half possessions — two TDs and a field goal — before finally forcing a punt on the opening drive of the second half against the Broncos' second offensive unit.

But to hear Packers middle linebacker Nick Barnett tell it, there's nothing to worry about.

"I definitely feel we have to clean some things up, but I'm not overly concerned," Barnett said. "I'm not saying the Titanic is sinking. It's definitely not. We just have some things we need to clean up. Other than that, I think we're fine."

Green Bay's defense played without run-stuffing defensive tackle Ryan Pickett, who missed his third straight game with a pre-camp hamstring injury, and linebacker A.J. Hawk, who missed his second straight game with a chest injury suffered in the exhibition opener against Cincinnati. Colin Cole started in Pickett's place, while Brandon Chillar made his second straight start for Hawk.

After forcing three straight three-and-outs in the preseason opener against Cincinnati before calling it a night after nine plays, the No. 1 defense got stops on its first four possessions against San Francisco last week (punt, punt, interception, punt) before allowing an 87-yard touchdown drive by the 49ers that ate up 9 minutes, 15 seconds and saw San Francisco pick up three third-down plays before scoring on a fourth-and-inches run.

On Friday night, the Packers allowed the Broncos' three first-half scores every way possible, as they were gashed by the run during the 99-yard march and blitzed by two Jay Cutler-to-Brandon Marshall deep balls — one drawing a 31-yard pass-interference penalty on Tramon Williams, the other resulting in a 49-yard touchdown against Williams on virtually the same play — on the next series.

The Broncos' first possession went 58 yards in 12 plays, with the Packers committing a 12 men on the field penalty on a fourth-down play and Al Harris giving up a 22-yard completion to Marshall on third-and-9 to keep the drive going, but linebacker Brady Poppinga stuffed Andre Hall on a first-down run. After back-to-back incompletions by Cutler, Denver settled for a field goal.

That didn't happen on the next drive, though. Starting at their own 1-yard line after Jon Ryan's 59-yard punt, Cutler hit fullback Peyton Hillis for a 14-yard gain on a short pass on third-and-8 from the Denver 3-yard line.

Hall burst up the middle past Johnny Jolly and Barnett for an 18-yard gain on the next play, and Selvin Young then converted the next third down with a 5-yard run. Cutler's 11- and 12-yard completions on back-to-back plays then set up a third-and-2 from the Packers' 9, where fullback Michael Pittman converted one play before Cutler's 7-yard touchdown to Nate Jackson.

"The big drive was disappointing," Packers coach Mike McCarthy said. "The strength of our defense has always been third down. We weren't as sharp tonight as we have been. We need to tackle better. That's two weeks in a row that the run defense was not as productive as it has been. Getting off the field on third down, that's the strength of our defense. We're better than we showed."

"We have to sure up some fundamentals — we missed a few tackles, missed a few gap controls, things we can easily adjust and get to," added defensive coordinator Bob Sanders, whose unit allowed Denver to go 8-for-15 on third down. "You're always concerned when they move the ball on you, so we will look and see and go from there."