The NFL season is finally upon us, and one of Week 1is marquee matchups will be the Green Bay Packers and their high flying offense against San Francisco and their stout defense, which ranked among the league's best in 2011.

It's been a tale of two offseasons for both of these franchises. On one side, you have the 15-1 regular season Green Bay Packers, who, depsite their season best record, had the league's 32nd ranked defense, and will be relying largely upon the contributions of rookies to boost their pass rush, namely first round pick Nick Perry, who is transition from defensive end to outside linebacker, and second and fourth round picks Jerel Worthy and Mike Daniels along the defensive line, respectively.

The loss of Nick Collins has also seen Charles Woodson move to safety in the Packers' base defense, so that will be one position to watch, as the Packers no longer have the services of Nick Collins at safety.

For San Francisco, it was all about becoming more explosive on offense, and in order to do so, they signed Rany Moss, who gets another shot to make one more run. They also drafted receiver AJ Jenkins in the first round, who has turned into a project with his early struggles, drafted running back LaMichael James in the second round out of Oregon, and signed former Giants receiver Mario Manningham to add to their receiving corps.

For the Packers, one of the keys to the game will be how their questionable secondary will fare against a Randy Moss, who, depsite his numbers, did not play at all last year, and it is uncertain how much he really has left in him. With a healthier Tramon Williams, the Packers may match up well, but unless this group improves its tackling, we could see the beginning of a very capable Alex Smith passing attack with this group of 49ers receivers.

For San Francisco, they key will be to give the Packers limited possessions, and that means sticking to what they do best: running the football. Frank Gore has shown he still has some gas left, and the 49ers have plenty of depth at the position with second year back Kendal Hunter and another former New York Giant in Brandon Jacobs to pound the ball against a Packer defense that struggled in all aspects last season.

On defense, the key for the Packers will be to stop the run and establish a pass rush against Aex Smith. A big part of the Packers' 2011 32nd ranked defense was the lack of a pass rush opposite Clay Matthews. The Packers have hoped to address that need with first round pick Nick Perry, but there wil inevitably be growing pains as a rookie transitioning from playing with his hands in the dirt rather than in a two point stance.

The addition of second rounder Jerel Worthy to play in the Packers' nickel defense will also be needed to help take pressure off of BJ Raji.

On defense, the key will be to get Aaron Rodgers off the field as quickly as possible, and keep him out of the endzone. Rodgers is dangerous with both his arm and his legs, and can buy himself second chances in the pocket and take off should there be an open field. The element of surprise, however, may be the Packers' running game with the addition of Cedric Benson during training camp, who showed he may have some production value left, and could give the Packers that threat in the running game they have been missing, as James Starks, who could be that back, has had trouble staying healthy.

Overall, this Week 1 matchup will be a fun one to watch, and it's very possible that, despite who emerges as the victor, we could see both of these teams play each other again in the NFL playoffs.