5 Biggest Things to Watch for in San Francisco 49ers Opener

The San Francisco 49ers and Green Bay Packers open the season on September 8 with a rematch of the NFC divisional game, when Niners quarterback Colin Kaepernick ran for a record 181 yards to lead his team to a 45-31 victory.

Kaepernick is expected to dominate again on Sunday, but the rest of the roster is filled with question marks. The offense is missing some key players, and the defense will be challenged by the Pack Attack.

While the opener does not always foreshadow the rest of the season, San Francisco is eager to get off to a hot start before playing NFC West rival Seattle Seahawks in Week 2.

5. Can the Offensive Line Live Up to Expectations?

San Francisco's front line of Joe Staley, Mike Iupati, Jonathan Goodwin, Alex Boone and Anthony Davis is a nasty, grinding force.

Every starter weighs over 300 pounds, as do reserves Daniel Kilgore, Joe Looney and Adam Snyder. Rotoworld ranked the Niners O-line as the second best in football, trailing only the New England Patriots. 

The 49ers brought in former head coach Eric Mangini as a senior offensive consultant. The Man-Genius is charged with keeping the Niners offense from being predictable, CSN's Matt Maiocco said.

Former St. Louis Rams safety Craig Dahl told Maiocco his old defense knew San Francisco's plays based on the offensive personnel. Mangini will likely implement run and pass plays with an unusual number of linemen.

Green Bay finished fourth in sacks last season but lost linebacker Dezman Moses, who had the third most on the team. Clay Matthews and B.J. Raji are the Packers' strongest pass-rushers, so San Francisco will need keep them out of the backfield.

4. How Will the Secondary Respond?

One of the NFL's best aerial attacks is coming to Candlestick Park, and the 49ers better be ready.

Packers quarterback Aaron Rodgers could hit Jordy Nelson over the middle, swing the ball to Randall Cobb or find James Jones on a deep fade. Heck, tight end Jermichael Finley might even get some love.

Cornerbacks Carlos Rogers and Tarell Brown need to lock down the sidelines while hard-hitting safeties Donte Whitner and Eric Reid patrol the middle. Rogers struggled at times last season after picking off six passes in 2011.

Green Bay rarely runs the ball, so the Niners will play reserve cornerback Nnamdi Asomugha and safety Craig Dahl or drop linebackers Patrick Willis and Navarro Bowman into coverage.

With All-Pro safety Dashon Goldson gone to free agency and third corner Chris Culliver out with a torn ACL, the secondary will be tested on Sunday.

3. Will Aldon Smith Dominate Again?

Outside linebacker Aldon Smith exploded for 19.5 sacks in the first 13 games last year, then couldn't get another in three regular-season games and three playoff games. So what happened?

There are three theories going around on why Smith disappeared. First and most obvious, he tore his labrum in Week 12 and needed surgery after the season. 

Smith's shoulder injury probably slowed him down, but he could play through the pain. His production was likely hurt by defensive tackle Justin Smith's absence over the final two-and-a-half weeks.

The Smiths' combination of power and speed wreaked havoc on offensive linemen, but Aldon suddenly got much more attention when Justin was gone. 

Finally, offenses have started paying more attention to Smith. As Pre-Snap Reads' Cian Fahey said, he was not considered a premier pass-rusher before last season and often matched up against one weak lineman.

Smith will not sneak under anyone's radar in 2013, so the third-year player will need to prove he can perform in the spotlight.

2. How Much Is Left in Frank's Tank?

Running back Frank Gore and tight end Delanie Walker were the leaders of San Francisco's smashmouth attack last season. To return to the Super Bowl, the Niners will need Gore to be productive without his partner in crime.

Walker has moved on to the Tennessee Titans, and voters in B/R writer Maxwell Ogden's poll said replacement Chris Harper is unlikely to deliver the same bone-crushing blocks.

At 30 years old, Gore is sure to slow down at some point but dodged Father Time and linebackers alike last year. He rumbled for 1,214 yards and eight touchdowns while averaging 4.7 yards per carry.

Running backs age quickly because they are expected to absorb bruising hits while maintaining elite quickness. As a Sports Illustrated slideshow demonstrated, even elite backs like LaDanian Tomlinson, Eric Dickerson and Marshall Faulk promptly became ineffective at age 30.

Gore has a chance to buck the trend if he continues to attack the middle. The Niners can run speedsters like Kaepernick and Kendall Hunter on the outside, so Gore may find more room between guards and tackles.

1. Who Will Catch the Ball?

Kaepernick's favorite target, wide receiver Michael Crabtree, is unable to practice for at least six more weeks with a torn Achilles tendon. The Niners are also without Mario Manningham, who is recovering from various knee injuries.

With limited options on the table, San Francisco brought in Super Bowl nemesis Anquan Boldin, who is fairly productive but turns 33 in October. 

Kyle Williams returns from ACL surgery to find himself the de facto No. 2 receiver. Backups Marlon Moore and Jon Baldwin have combined for just 53 receptions over five NFL seasons, so rookie Quentin Patton could get some playing time early on.

Tight end Vernon Davis thrived with Alex Smith under center but was targeted just nine times in the last six regular-season games.

The Niners receiving corps are the roster's weakest link, and Kaepernick needs to find a new go-to guy. All eyes will be on Boldin, Williams and Davis as they vie for his attention.