In every Super Bowl there is an unheralded guy who plays a critical role in the outcome of the game.
This X-factor, as we like to call them, could be one of the team's key starters, or it might be a backup player who rises to the occasion in a critical moment.
Regardless, he makes a play, changes the game's momentum and ultimately becomes the deciding factor.
Given their importance, let's take a look at some of the X-factors that could emerge in Super Bowl XLV:
Offense: Doug Legursky, center
The venerable veteran steps in for a Pro Bowler (Maurkice Pouncey), and he will need to play at an elite level to keep the Steelers' offense afloat against a rugged Packers defense. Facing Dom Capers' exotic blitz scheme will test his football acumen, but the battle with B.J. Raji and Ryan Pickett will try his strength, leverage and toughness. How well he fares against the Packers' powerful tandem could be the deciding factor in Super Bowl XLV.
Defense: Ryan Clark, safety
Clark plays an interchangeable role in the secondary with Troy Polamalu, but he will play a critical role as the deep middle safety against the Packers' vertical passing game. As the last line of defense, he must eliminate the Packers' deep ball and make Rodgers settle for short throws or check downs. He also needs to set the tone for the game by putting a big hit on one of Green Bay's receivers to strike fear in the hearts of anyone venturing into the middle of the field. By knocking pass catchers around, he can disrupt the rhythm of the passing game and change the way that the Packers choose to attack the Steelers' defense.
Special teams: Shaun Suisham, kicker
He has been rock-solid since taking over kicking duties in the middle of the season, but has been a little shaky during the playoffs. While inclement weather played a role in his unsteadiness, he gets a chance to play in perfect conditions in Cowboys Stadium. With a range that extends to 50 yards, he could provide a stream of points for the Steelers when they enter Packers territory. If he is able to put the ball through the uprights with the game on the line, he could be the deciding factor.
Green Bay Packers
Offense: Jordy Nelson, wide receiver
The third-year pro has quietly emerged as one of Aaron Rodgers' favorite targets during the postseason. A big, physical receiver with outstanding quickness and excellent hands, Nelson feasts off sub-defenders from the slot. He does a great job of gaining separation from tight coverage and has a knack for finding open windows. Against a Steelers defense that employs a lot of two-deep coverage, he could find plenty of openings over the middle of the field. Given the importance of converting third downs against a stingy defense, Nelson could play a major role.
Defense: B.J. Raji, defensive tackle
Raji sealed the game against the Bears in the NFC Championship game with a pick six, and he figures to play a prominent role in Super Bowl XLV. He is a big, athletic defender with outstanding strength and movement skills. He has the potential to thrive in a three-dimensional role as a run stopper, pass rusher and zone-dropper in the Packers' defense. For the Packers to win, he must limit Rashard Mendenhall's effectiveness on the ground while also providing a consistent rush on Ben Roethlisberger in the pocket. If he can also show some versatility as a zone dropper, he could be a pivotal pawn in Capers' winning game plan.
Special teams: Tim Masthay, punter
The tightly contested nature of this game could make it come down to a battle in field position. Masthay was masterful with his directional kicks in the NFC championship, and the Bears spent most of the game working from the shadow of their own end. Against the Steelers, he must keep the ball in the corners to force Ben Roethlisberger to drive the length of the field against the Packers' stingy defense. If the combination of solid kicking and stingy defense results in short fields for Green Bay's offense, Masthay might rank as the most valuable player at game's end.