AP

The San Francisco 49ers earn the top spot in our preseason power rankings after a trip to the Super Bowl last season.

Quarterback Colin Kaepernick took over the helm midseason and was able to get the 49ers past their NFC Championship game appearance of 2011 and back to the game’s biggest stage. While the 49ers ultimately fell a few plays short of a title, they enter the 2013 season as a championship contender once again.

The 49ers will need to stem the tide of injuries to key players early in the season and find adequate replacements for a few departed veterans. They’ll also have to navigate perhaps the toughest division in the NFL but the outlook for the 49ers is still rosy as training camp gets underway.

Strengths.

The 49ers offensive line has been among the best in the league for several seasons. The starting group of Joe Staley, Mike Iupati, Jonathan Goodwin, Alex Boone and Anthony Davis started all 16 games last season. Staley and Iupati both were selected to the Pro Bowl last season with Boone as an alternate. Adam Snyder is a veteran that should be able to fill-in adequately at guard should either Iupati or Boone go down with an injury as well.

San Francisco linebackers are also among the strongest units in the league. As with the offensive line, the linebacking corps for the 49ers was remarkably durable as the four starters each started all 16 games last season. Patrick Willis and NaVorro Bowman form a formidable tandem inside and Aldon Smith has quickly become one of the best pass rushers in the league in his first two seasons. Parys Haralson is returning after a torn triceps forced him to miss all of last season and third-round pick Corey Lemonier adds even more depth to an already strong group.

Weaknesses.

With Michael Crabtree out for the foreseeable future with a torn Achilles and Mario Manningham and Kyle Williams on PUP while working back from ACL tears, the 49ers have serious questions at the wide receiver position. Anquan Boldin is a solid veteran option but he’s adjusting to his new team. A.J. Jenkins saw just one target in a wasted rookie season. The 49ers need Jenkins, Ricardo Lockette or fourth-round pick Quinton Patton to become contributors to bridge the gap until Crabtree and Manningham get healthy.

Vernon Davis is one of the best tight ends in the game. However, the loss of Delanie Walker to Tennessee will be a blow – especially if Davis is needed to help at receiver with the mounting injuries outside. Garrett Celek appeared in 13 games last season but isn’t much of a receiving option. Second-round pick Vance McDonald could fill the role of the departed Walker and be the complementary tight end the 49ers need.

Changes.

The trade to acquire Anquan Boldin from the Ravens this offseason has become a pivotal move for the 49ers following the Achilles injury to Crabtree. Manningham and Williams are still working back from knee injuries and Boldin will be the only option with any real experience and proven production until they can return. San Francisco added cornerback Nnamdi Asomugha, defensive tackle Glenn Dorsey and safety Craig Dahl to add depth on the defensive side of the ball. Kicker Phil Dawson looks to solidify a position that was wildly inconsistent with David Akers last season.

Quarterback Alex Smith left to take over the starting job for the Kansas City Chiefs. The 49ers signed Colt McCoy from Cleveland to serve as the backup for Kaepernick. Tight end Delanie Walker left in free agency to sign with the Tennessee Titans. Nose tackle Isaac Sopoaga signed with the Philadelphia Eagles and safety Dashon Goldson signed a lucrative contract with the Tampa Bay Buccaneers.

Camp battles.

Cornerback should be one of the more intriguing battles of camp for the 49ers. Tarell Brown and Carlos Rogers starters all 16 games for the 49ers last year but should see competition from Asomugha for playing time. Chris Culliver also was a decent contributor for San Francisco at times last season and will be in the mix as well.

With the departure of Sopoaga to the Eagles, the 49ers will need to find a replacement along the defensive line. Dorsey is expected to compete with Ian Williams for the starting nose tackle job though Dorsey doesn’t have the traditional size attributed to a 3-4 nose tackle. Lamar Divens may have an outside shot at competing for the job as well if Dorsey or Williams don’t grab hold of the spot.

Prospects.

The San Francisco 49ers have one of the strongest rosters in the league and could be playing their best at the end of the season after players return from injuries. They’ll miss Crabtree early in the year and the receiving corps is very shaky with Manningham and Williams also working back from injuries. All three are likely to be back at some point during the season and the 49ers should be able to bridge the gap with enough victories to be in the playoff picture until they return. The running game will have to take on additional weight in the interim but Frank Gore and company should continue to shoulder the load well with Kaepernick bringing an added dimension as well.

The 49ers have been the benefactors of remarkable durability over the past few seasons, especially defensively and along the offensive line. Is the Crabtree injury a precursor of issues to come? The 49ers should expect a serious fight for the NFC West from the rival Seattle Seahawks as well and an improved St. Louis Rams team could continue to cause problems for the 49ers this season. At full strength the 49ers are as talented as any team in the league and should be in the hunt to make the Super Bowl once again.