The 49ers' defense versus the Saints' offense is the match-up that will decide this game.
San Francisco gave up 14.3 points per game in the regular season, compared to New Orleans' offense, which scored 34.2 points per game. For the 49ers to win, they cannot allow New Orleans to score more than 20 points.
The Smith Bros. (Aldon (OLB) and Justin (DE)) on the 49ers' defense will be on display in this game. Since the Saints are a pass first team, look for Aldon Smith to get more playing time.
The Smith tandem must get consistent pressure on Brees to force him to check the ball down to receivers running short routes.
With all the attention on the Smith Bros., expect 49ers linebacker Ahmad Brooks to have a good game rushing from the opposite side.
The 49ers' defense matches up well against the Saints' biggest and smallest receiving threats: tight end Jimmy Graham and running back Darren Sproles.
The 49ers' standout linebacker Patrick Willis will likely be called on to cover Graham. Willis has been successful covering big-bodied tight ends this season, such as Jermaine Gresham from the Cincinnati Bengals and the Detroit Lions' Brandon Pettigrew (both listed at 6'5").
San Francisco linebacker NaVorro Bowman, who was assigned to spy Philadelphia Eagles quarterback Michael Vick, will likely be covering Sproles. Bowman does not have the ability to lock down Sproles, but he is a sure tackler and will limit the yards Sproles gains after the catch.
If San Francisco can force Brees to dink and dunk all game, that will throw him off-rhythm and eventually lead to some big turnovers.