As I sit back and think about this matchup between two bitter, hated rivals, one X-factor really comes to mind: the matchup on the sidelines.
Giants' defensive coordinator Steve Spagnuolo learned under one of the best, Eagles defensive coordinator Jim Johnson.
"Spags" was the linebacker's coach under Johnson and now during his tenure in New York, has turned the Giants into one of the most-feared defensive units in the NFL.
Johnson meanwhile, continues to plug along and has turned loose his band of hungry vultures on opposing quarterbacks all season long. The chess match between the two will be something to keep an eye on.
Keys for the Giants
The biggest key for the Giants will be their ability to run the football to set up play-action pass downfield and open up passing lanes for Eli Manning. Brandon Jacobs and Derrick Ward each rushed for over 1,000 yards in 2008, the fifth duo to ever accomplish such a feat.
Fullback Madison Hedgecock and the offensive line, captained by Pro Bowl center Shaun O'Hara, deserve a huge amount of credit for not only providing open running lanes but a clean pocket for the Super Bowl MVP.
Manning threw only 10 interceptions to go along with 21 touchdown passes and a comfortable 3,238 yards.
The loss of Plaxico Burress to injury could prove to be key as the Giants now lack a true deep threat at wide receiver.
Burress' height and speed allowed defensive coordinators to roll coverages toward the 6'5'' hero of Super Bowl XLII with aggressive man coverage and a safety over the top.
Burress' absence has not deterred Manning's success and other receivers have stepped up, mainly Domenik Hixon (43 catches, 596 yards), Steve Smith (57 catches, 574 yards), and tight end Kevin Boss. He leads the team with six touchdowns; all of Boss' scores have come in the red zone.
The other key (well two keys in one) for the defending champions will be to contain Donovan McNabb and Brian Westbrook. As the Eagles have shown, they love to run the screen game and get Westbrook in open space matched up against linebackers and safeties.
The Giants could not stop Westbrook in their last matchup in week 14 as he gained over 200 yards in total offense (131 rushing, 72 receiving) with two touchdowns.
Steve Spagnuolo must devise a gameplan to not only pressure McNabb's receivers but his pocket as well. Big Blue must keep McNabb in the pocket and limit his ability to use his legs to extend plays.
The Giants had 42 sacks during the regular season, led by Pro Bowl defensive end Justin Tuck's 12.
Look for cornerback Aaron Ross to be matched up one-on-one against rookie DeSean Jackson and the linebacking corps led by Antonio Pierce to play spy coverage on both McNabb and Westbrook. The rest of the secondary must step up against a potentially explosive passing game.
As for Manning, ball security will be crucial. Manning was sacked 27 times yet had only two lost fumbles all season. His ability to hold onto the football against an aggressive, blitzing defense will be important in terms of time of possession and the field position battle.
Finally, the kicking game. Though they are 42 and 44 years old respectively, punter Jeff Feagles and kicker John Carney (both of whom made the Pro Bowl) will help the Giants in winning the field position battle.
Carney connected on 92 percent of his field goals and every one of his extra point attempts while Feagles continues to be consistent in his 18th season, forcing 23 touchbacks.
Keys for the Eagles
The Eagles offense starts and ends with running back Brian Westbrook. Even though he did not quite put up numbers like he did in 2007, Westbrook's presence affects the entire game. Of the 1,056 total offensive plays, 287 (about 30 percent) of them go through Westbrook.
As seen in the Wild Card matchup against Minnesota and the week 14 game in New York, Westbrook can change the game at the drop of a hat.
Donovan McNabb was benched after a terrible performance against Baltimore but has since struck back with phenomenal performances leading Philadelphia to this point.
Though not having an elite wide receiver like Terrell Owens in 2004, McNabb grew comfortable with rookie DeSean Jackson for big plays; Jackson averaged a little over 14 yards per catch.
The defense of the Eagles is an entirely different story. Under Jim Johnson, the NFL's fourth ranked defensive unit continues to make big plays when counted upon. The Eagles had 48 sacks during the regular season but that's only half the story. Of those 48 sacks, exactly half came off of a called blitz.
The Eagles also love to force turnovers; they forced 21 fumbles and gathered 15 interceptions. The concept of a Jim Johnson blitz comes from the school of Steelers coordinator Dick LeBeau: you don't know where it's coming from. Gap pressure and confusion of protection schemes is key in making the blitz work.
Philadelphia must contain the Giants running game and make Manning beat them through the air. Pressuring the pocket, an Eagles specialty, will be a vital key.
Pro Bowl cornerback Asante Samuel, acquired from the New England Patriots in the offseason, will be probably matched up against Domenik Hixon. His coverage skills will be important when the Giants spread the field with four wide receivers.
Safety Brian Dawkins continues to be the driving force behind the Eagles ball-hawking secondary. Though he may not be the player he once was, he continues to defy the odds and play at an extremely high level with three sacks, six forced fumbles and an interception. His leadership and field presence should make Eli Manning think twice before throwing a pass in his direction.
As I said in the Giants analysis, special teams will also be a key factor. Punter Sav Rocca and Pro Bowl kicker David Akers could dictate field position and maybe decide the outcome of the game in its late moments.
This game will come down to who makes the least mistakes and that does include penalties. With the swirling winds at the Meadowlands and the crowd in their favor, the Giants will have the home-field advantage but don't be surprised if Philadelphia hangs with them step for step.