The Packers are a different offense than the first time they played the 49ers.
And that may actually help the 49ers this time through.
As Matt Barrows of the Sacramento Bee points out, because Green Bay spent much of the opener spreading the field with four wide receivers, the 49ers fourth cornerback, Perish Cox, played more snaps than Pro Bowl middle linebacker Patrick Willis.
Willis and fellow inside linebacker NaVorro Bowman rotated quite a bit during that game, as the spent the majority of the day in dime defense.
But Cox played 51 of the 68 snaps against the Packers (he averaged 7.3 snaps a game in the other 15), while Willis played 46 snaps and Bowman 56.
Those two normally play nearly every snap, much of the reason the 49ers defense is so good.
Of course, the 49ers held the Packers in check fairly well in that matchup, limiting them to 324 total yards, with 279 of them through the air.
Only 138 of those yards (112 passing, 24 rushing) came in the first half, as a late rally made the Packers numbers look better than they actually were. But with the Packers getting more from their run game of late, they may not elect to take Willis off the field as much as they did the first time.