Packers vs. 49ers, NFL playoffs 2013: Will the 49ers slow down Aaron Rodgers?

The 49ers and Packers don't have very many secrets. San Francisco likes to run the ball and stop the run, while Green Bay is geared toward a high-powered passing attack and one of the best pass-rushing units in the NFL. When the two teams meet on Saturday, it will not only be a clash of styles, but it will match up two of the best units in the NFL.

The Packers offense against the 49ers defense is the highlight of the matchup, but ultimately may not be the key.

Green Bay offense vs. San Francisco defense

The strength of the 49ers' defense is stopping the run — and while the Packers don't run the ball well, they also don't rely on a strong running game. Green Bay wins games on the arm of Aaron Rodgers and the team's passing attack. Their lack of a running game may actually serve as a benefit against San Francisco, as it neutralizes one of the 49ers' strengths.

The Packers will likely try to take away another 49er strength by spreading the field with four wide receivers. As noted by Football Outsiders, San Francisco rarely used a dime personnel package during the season, instead preferring to stick with their base and nickel packages. If Green Bay spreads the field, they could force the 49ers to use dime cornerback Perrish Cox. The 49ers allowed an average of 1.93 more yards per pass attempt when Cox was on the field this season.

Going against a tough defense, Green Bay will need to capitalize on their scoring opportunities, something they did very well during the regular season. The Packers scored touchdowns on 68.1 percent of their red-zone opportunities, well above the league average of 54.2 percent. San Francisco allowed touchdowns on 61.1 percent of opponent red-zone possessions.

With their likely reliance on passing, the Packers will need to protect Rodgers. Green Bay allowed a sack on 9.1 percent of pass attempts, nearly 3 percent above the league average. Led by Aldon Smith, San Francisco finished the season with a sack rate of 6.7 percent.

San Francisco offense vs. Green Bay defense

The 49ers had one of the NFL's best rushing attacks during the first half of the season, but have not had the same success recently. Over the first seven games of the season, San Francisco averaged 176.6 rushing yards per game and 5.9 yards per attempt. Those numbers declined to 139.4 rushing yards per game and 4.5 per attempt over the final nine games.

Even with recent struggles, the 49ers are still likely to run the ball and run it early. San Francisco ran the ball 50.7 percent of the time on first down and had a lot of success, gaining 4.9 yards per first-down rush. That helped keep the 49ers out of long-conversion attempts. San Francisco converted 35.1 percent of its third downs, below the league average of 38.2 percent. The 49ers were even worse in long situations. On third-down plays with at least six yards to go, San Francisco converted just 28.6 percent of the time. While the Packers defense may not be as good as San Francisco's, Green Bay does an excellent job on third down. The Packers allowed just a 33.0 percent third-down conversion rate.

San Francisco's running game is key to not only reducing the pressure on Colin Kaepernick, but also to reducing the pressure on San Francisco's offensive line. The 49ers allowed a sack on 9.4 percent of pass attempts, the third-worst rate in the NFL. While San Francisco struggled, Green Bay's defense had the fourth-best sack rate in the league at 8.3 percent.

So, what does it all mean?

Despite their different offensive styles, San Francisco and Green Bay are very evenly matched. Not many teams can slow the Packers' passing offense, but San Francisco may be one of the few. The 49ers, however, will need to get their running game going early if they are going to avoid the Packers' pass rush from pinning their ears back.

While all of the eyes will be on the matchup of Green Bay's offense against the San Francisco defense, there is a good chance this game will come down to the 49ers' offensive line against. the Green Bay defensive line. If San Francisco runs the ball like they did early on, they will have an advantage. If not, Green Bay could be in prime position to pull off the road upset.