The Baltimore Ravens and San Francisco 49ers will meet in Super Bowl XLVII at the Superdome in New Orleans on Sunday to decide which team gets to hoist the Lombardi Trophy as the champions of the National Football League.Here's a preview of the Super Bowl:

Super Bowl XLVII — Baltimore Ravens vs. San Francisco 49ers

Mercedes Benz Superdome, New Orleans; 6:30 p.m. (ET) on CBS; Line: 49ers by 3.5 points

The Baltimore Ravens are making their second Super Bowl appearance, while the San Francisco 49ers will be making their sixth. Neither franchise has ever lost a Super Bowl. The Ravens defeated Indianapolis, Denver and New England to win the AFC crown. The 49ers beat Green Bay and Atlanta to capture the NFC title.

The teams are coached by brothers John and Jim Harbaugh. Older brother John, 50, guides Baltimore, while Jim, 49, is at the helm for San Francisco. Both coaches made crucial personnel changes during the season that helped get their teams to the Super Bowl. John Harbaugh replaced offensive coordinator Cam Cameron with Jim Caldwell on Dec. 10. Jim Harbaugh switched from veteran quarterback Alex Smith to second-year player Colin Kaepernick in early November. Both teams improved after the changes. Each team must execute a few crucial parts of its game plan on Sunday to win Super Bowl XLVII.

Keys to a Baltimore Ravens' victory:

• Protect the quarterback. Ravens quarterback Joe Flacco has been stellar this postseason, compiling a passer rating of 114.7 with eight touchdowns and no interceptions. He's had time to throw in all three games and has spread the ball around to Torrey Smith, Anquan Boldin and Jacoby Jones. Flacco's deep passes open up the Baltimore running game, led by Ray Rice and Bernard Pierce. The 49ers pass rush, led by Aldon Smith, can be fierce. However, Smith hasn't registered a sack in the last five games.

• Contain the 49ers backfield. Baltimore's defense has beaten playoff teams quarterbacked by Andrew Luck, Peyton Manning and Tom Brady, all proficient dropback passers. San Francisco has a much different attack. Kaepernick and running back Frank Gore can roll up yardage and then strike downfield with a play-action pass when the defense is off balance. Forcing the 49ers into passing downs will allow the Ravens defense to be physical in pass coverage, as they have been in their three wins. A human tackling machine, Baltimore linebacker Ray Lewis will be playing the last game of his 17-year NFL career. He'll leave all his energy on the field.

• Win the turnover battle. From cornerback Corey Graham's interception in Denver to safety Bernard Pollard's forced fumble against New England, the Ravens have come up with big turnovers to win in the playoffs. If Flacco or Rice are careless with the ball, or Kaepernick doesn't make mistakes, Baltimore's chances of winning decrease.

Keys to a San Francisco 49ers' victory:

• Jam the Ravens' receivers. Flacco sets up the run — and controls the tempo of the game — through the pass. He will test San Francisco cornerbacks Tarell Brown, Carlos Rodgers and Chris Culliver with a variety of routes and receivers. The 49ers' secondary must be physical and keep Smith, Jones and Boldin from getting open down field, on the sidelines, and across the middle.

• Stay poised. The only times San Francisco has struggled since Kaepernick took over were road losses to St. Louis and Seattle. During both games, the second-year starter was pressured and looked frazzled. Kaepernick can make the zone-reads quickly, but if he hesitates, a veteran Baltimore defense, featuring Lewis, Ed Reed and Paul Kruger, could force mistakes.

• Control the line of scrimmage. The 49ers need defensive tackle Justin Smith to help control the line of scrimmage to amplify the pass rush and stuff the run. The more attention the Ravens pay to Smith, the more they may put a single blocker on linebacker Aldon Smith. On offense, San Francisco will run Gore between the tackles. They'll need to get a push on the Baltimore defensive line, anchored by Haloti Ngata and Ma'ake Kemoeatu.