Defense has been one of the biggest question marks in recent years when it came to the viability of the Green Bay Packers as a Super Bowl contender.
So far, it's not a problem after the first four games of the regular season.
Move over, Aaron Rodgers -- the Packers' defense is rolling too.
"They always say defenses win championships. As long as we're all playing on all cylinders, we can't be beat," outside linebacker Nick Perry said. He had two of Green Bay's six sacks in a 17-3 win Sunday over the San Francisco 49ers.
The Packers (4-0) are using a familiar formula on defense in focusing on stopping the run to turn teams into a one-dimensional passing offense.
When Green Bay's offense scores in bunches, it helps the defense even more because pass rushers such as Perry can concentrate on getting to the quarterback with the opponent playing catch-up.
Four weeks of improvement built up to a dominating performance in San Francisco. The Packers held the 49ers to 77 yards rushing and 196 yards overall. The defense has 13 sacks over the past two games.
Green Bay has come a long way from the season opener, when Chicago's Matt Forte hurt the Packers for 141 yards on 24 carries.
"Four wins and getting better each and every week on defense is what you're looking to do," coach Mike McCarthy said Monday evening at Lambeau Field.
A tough defensive front added Letroy Guion back into the mix to join leaders Mike Daniels and B.J. Raji. Clay Matthews is getting more opportunities at rushing the passer the past two weeks after being relied upon more at inside linebacker the first two weeks.
And the Packers are getting contributions from all their edge rushers, starting with Julius Peppers. Emerging playmaker Jayrone Elliott is getting more snaps in a deep rotation that also includes Perry and Mike Neal.
Seven Packers have at least one sack, with Peppers (3 1/2 sacks) leading the way. With three sacks, Perry, a first-round pick in 2012, is already just one away from matching his career high.
"I like the rotation that we have going with our front group and Nick has done a really good job taking advantage of those opportunities," McCarthy said.
NOTE: McCarthy said that right tackle Bryan Bulaga feels stronger, but a decision on the next step as he returns from a left knee injury will be made on Wednesday morning before the team's next practice. I know Bryan feels likes he's getting stronger," McCarthy said. Bulaga hasn't played since the season opener against the Bears.
