What a difference four months can make.

On Sept. 9, 2012 the Green Bay Packers hosted the San Francisco 49ers in the regular season opener at Lambeau Field. The Packers were set on rinsing the bad taste out of their mouths following a home playoff loss to the New York Giants. The 49ers felt they were a team on the rise after pushing those same Giants to the brink in the NFC Championship game.

Yet it was the Packers who captured the minds of many national pundits heading into the season. With MVP quarterback Aaron Rodgers and all of his weapons returning, many national pundits (and fans) had penciled the Packers in a Super Bowl entrant.

Then the game was played, and the 49ers raced out to a 23-7 lead, and then 30-15, before finally winning 30-22.

Several weeks later, the 49ers were deemed the best team in the NFL; the Packers as a reeling, injury-plagued also-ran.

So much has changed.

Pro Bowler David Akers hit a 63-yard field goal for the 49ers in that game. Six days ago, head coach Jim Harbaugh was bringing in kickers to challenge the now unreliable 38-year-old.

Donald Driver raced out of the tunnel to a thunderous applause. Over the weekend he was declared inactive, and later retweeted many of the positive "end of an era" messages fans sent his way.

Four Packers starters that day have been long lost due to injury, two others (Jarrett Bush, Jeff Saturday) long ago replaced for better options.

The 49ers have fared better on that front, with just one starter from that game (Kyle Williams) on IR, but the team dynamic has clearly changed following the replacement of Week 1 starter Alex Smith with Colin Kaepernick.

And, free agent acquisition Mario Manningham (four catches in Week 1) is also on IR.

Following that Week 1 showdown the 49ers became the darlings of the NFL by late November, deemed the best team in the league after a 32-7 prime time dismantling of the Chicago Bears in Kaepernick's first start and an impressive road win in New Orleans.

That same week, the Packers were thrashed in prime time by the Giants, 38-10, and sat at 7-4. They weren't quite in disarray, but you could say not many outside the locker room had much confidence in the team's prospects.

Then, the 49ers lost to the St. Louis Rams, held on for a shaky victory over New England and were blown out by Seattle. The Packers rattled off four straight wins.

Suddenly, Rodgers was back in the MVP conversation, and people questioned Harbaugh's decision to roll with the inexperienced Kaepernick.

Oh, but two weeks ago the Packers lost at Minnesota and the 49ers won in Arizona, flip-flopping seeds and giving the 'Niners a bye and a home game.

Now, we wonder how the long flight will affect the Packers, how playing near his hometown may affect Rodgers, how the bye will help Harbaugh prepare.Talk about flip-flopping.

So what do we actually know about this game Saturday night?

Packers fans can take comfort in knowing Clay Matthews (2.5 sacks Week 1) can beat the 49ers offensive line, but then again Kaepernick is a far more elusive target than Smith.

Adrian Petereson was finally corralled on Saturday, but prior to his monster games in the regular season Frank Gore was the only other running back to top 100 yards against the Packers defense.

Randall Cobb had his breakout performance with nine catches and a kick return touchdown, but that was four months ago – he's now the No. 1 focus of the 49ers defense and he is being weaned off special teams.

So what do we know?

Turns out, not much.