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 be wearing a Super Bowl blemish for the first time after Sunday's title game in the Superdome.
The Ravens (13-6), who are 3 1-2-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.
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.
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.
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.