NEW ORLEANS >> The San Francisco 49ers never have tasted defeat in a Super Bowl, going 5-0. It’s the most impressive mark for any franchise in the big game.

Baltimore also is undefeated, with the Ravens winning their only appearance, in 2001.

Someone will have the Super Bowl blahs for the first time after Sunday’s title game in the Superdome.

The Ravens (13-6), who are 3½ -point underdogs, are on one of those runs reminiscent of recent NFL champions. Indeed, the New York Giants reached the Super Bowl a year ago in a similar manner, winning a wild-card game at home, then two playoffs on the road, including an overtime thriller.

The Giants got healthy down the stretch, something the Ravens have replicated, particularly on defense where star linebackers Ray Lewis and Terrell Suggs are giving vintage performances following injury-shortened seasons.

“I believe we have found a way to believe in each other, and nothing else matters,” said Lewis, who will retire after the game. “That is one thing about our sideline. When we are on our sideline, there is only one thing that matters, when this game ends, we will be victorious, and everybody believes the same thing. That’s what’s been our road, no matter who’s been up, who’s been down, who’s been hurt, who’s been injured. We found a way to pick each other up.”

Baltimore’s path to New Orleans led through New England, where the Ravens fell to the Patriots in last year’s AFC title game. But they outscored the Patriots 21-0 in the second half to earn their spot in the Super Bowl.

San Francisco (13-4-1) also came up one win short a year ago, losing to the Giants for the NFC championship. That defeat has driven the 49ers just as much as the Ravens’ failure in 2011 lifted them.

These Niners are built around a physical, stingy defense — that also has been the Ravens’ persona for years, although not as much in 2012 as in Lewis’ other 17 pro seasons. Linebacker Patrick Willis, who like Lewis wears No. 52 and is a perennial All-Pro, is the anchor.

“As a kid, you grew up watching,” Willis said. “Just to have the opportunity to be able to play in this game given my first four years (out of the playoffs), we were at home at this time watching other teams play. Last year we were one game away. To be able to be here, is truly special.”

To make it extra special, San Francisco’s offense will need to outdo Baltimore’s. The Ravens have scored 90 points in three games, and the Niners have 73 in two.

Baltimore’s defense has made big plays against Andrew Luck, Peyton Manning and Tom Brady. Now it gets an entirely different type of quarterback, Colin Kaepernick. His combination of running skill, powerful arm and surprising cool for a second-year pro makes him particularly dangerous against the Ravens. Baltimore does not have the fastest defense in the league.

Then again, the 49ers must deal with Joe Flacco, the only QB to win a postseason game in each of his first five seasons. Flacco also has six road playoff victories, a league record.

He’s also outplayed Brady, the most successful quarterback of the last dozen seasons, in two straight AFC title games.

But he has his critics because this is his first Super Bowl trip in five tries.

“I think there is definitely a part of all of us that hear things and when somebody doubts what you want to do, you definitely go show them that they may be wrong,” he said. “I think for the most part we play for each other and that stuff is kind of a secondary issue.”

While the Ravens and 49ers play for each other, the Harbaugh brothers, John of the Ravens and Jim of the 49ers, will go against each other in the first Super Bowl featuring sibling head coaches. They’ve had fun with the topic this week, but it will be as serious as football can get on Sunday.

With older brother John coming out on top.

RAVENS, 27-24