When the Packers and Steelers kick-off this afternoon (at 4:30pm MT) in Dallas, many will be wondering if the offensive units can move the ball against the stingy Green Bay and Pittsburgh defenses. 'Offense wins games, defense wins championships.' And special teams just might be the difference maker in Super Bowl XLV.

On opposite sidelines of Cowboys Stadium stand the AFC champion Pittsburgh Steelers and NFC victor Green Bay Packers, storied franchises that have combined for nine Lombardi trophies and 18 NFL championships and embody the NFL's past and present. While the game has changed since those eras, the philosophy of denying opponents a measly inch, let alone a yard, remains alive, well and best symbolized by this year's title pairing of strikingly similar 3-4 defenses coordinated by two men linked by their like-mindedness.

"It could be a low-scoring game, but we'll see," Packers cornerback Tramon Williams said. Las Vegas betting lines suggest about 45 total points.

The Steelers, who have six defensive players in the Pro Football Hall of Fame, enter the game with a unit that could ultimately send a few more to the Canton, Ohio, shrine regardless of whether they win their third Super Bowl in six years and record seventh overall. They allowed a league-low 232 points in the regular season (14.5 a game) and have yielded 1,048 since the start of the 2007 season (16.4 a game).

Pittsburgh's 276.8 yards allowed a game put them second only to the San Diego Chargers, who missed the playoffs. The Steelers rank first or second in most defensive categories.

While they resist comparing themselves to Pittsburgh's "Steel Curtain" defenses of the 1970s, the fabric of those clubs clearly lives on in a team on the cusp of another dynasty.

"Pittsburgh has as much tradition on defense as anyone," Steelers defensive end Brett Keisel said. "You talk about the old Steel Curtain days. When those guys played you, they were going to come get you. … You didn't have to look for them; they were looking for you. To be able to be a part of that is something I take a great deal of pride in.

"We just need to win one more game, and maybe they'll talk about us a little bit like they talked about those guys."

Their mission is slowing the Packers' runaway train of an offense that is averaging 369 yards a game in the postseason and is engineered by quarterback Aaron Rodgers (six touchdowns, two interceptions, 109.2 rating). But Green Bay, which has seven defensive legends in the Hall of Fame, counters with a defense keenly aware of and intent on maintaining club tradition.

The Packers have earned a fifth Super Bowl appearance by neutralizing offensive juggernauts in the Philadelphia Eagles and Atlanta Falcons and forcing the Chicago Bears to use three quarterbacks. Their 282.3-yard defensive average in the playoffs trails the Steelers by about 75 yards, yet the Packers have threats from the line to the secondary — including a potential Hall of Famer in cornerback Charles Woodson. Not bad for a unit that lost three opening-day starters to season-ending injuries.

So as the offenses attempt to compile yards and points, the defenses will determine whether those quests involve a short field or end up as a long day. Considering histories and commonalities, maybe that's how it should be.