Key To Indianapolis' Offense: The Colts go as WR Marvin Harrison goes. He's been the NFL's best receiver this season, and QB Peyton Manning knows how to get him the ball. Harrison set the single-season receptions record this year (finishing with 137) and reached 600 catches faster than any other receiver in NFL history.
Key To Defending It: Play lots of "overtop-and-underneath" coverage, where the corner bumps Harrison at the line and stays with him underneath while the safety stays above him. And hit him. He likes to catch the ball on the outside quarter of the field, enabling him to get out of bounds if needed. Force him to the middle of the field, so you can hit him early and often.

Key To New York Jets' Offense: RB Curtis Martin is the main man in the Jets' offense. He's now rushed for 1,000-plus yards in eight straight seasons. When he's on, he makes life much easier for QB Chad Pennington, who has had a superb season.
Key To Defending It: Commit eight men to the box and do your best to stop the run. Pennington is in just his third year in the NFL, and he didn't even begin the season as the Jets' starter, so see how he thrives under playoff pressure. Don't let Martin control the game.

Key To Oakland's Offense: The diversity of weapons, from QB Rich Gannon to WRs Tim Brown and Jerry Rice to RBs Tyrone Wheatley and Charlie Garner. Gannon manages a West Coast attack that relies on precise routes and timing.
Key To Defending It: Play bump-and-run on the corners and in the slot. Press their receivers by getting up on the line of scrimmage with your defensive backs. Play physical -- hit the receivers at the line of scrimmage. Take a couple of penalties if you have to, but don't allow them a free release off the line.

Key To Pittsburgh's Offense: Their wide receivers -- especially Hines Ward, who is the catalyst and emotional leader. Plaxico Burress is also outstanding. The quarterback situation has fluctuated due to ineffectiveness and injury, but these two wideouts have been the constant.
Key To Defending It: Play a Cover-4, which means the cornerback and safety on each side are responsible for the receiver on that side. So it's basically two-on-one coverage every time. Against Ward and Burress, it's tough to play one-on-one or a deep zone. But you'll probably give up rushing yards.

Key To Tennessee's Offense: QB Steve McNair is doing something you aren't supposed to be able to do -- not practice (because of injuries) and still play well. He's the key for the Titans. His stats aren't always pretty, but he gets the job done.
Key To Defending It: McNair is tough, but he isn't super-fast or explosive like Michael Vick. So play disciplined, solid defense without focusing on anyone on the Titans. Mix up your coverages from zone to man. Be prepared to play a fundamentally sound game.

NFC playoff teams
Key To Atlanta's Offense: QB Michael Vick, of course. Vick has done so much in just his first season as the starter. It's difficult to prepare for him on film -- he's so creative and explosive that he rarely does the same thing twice. The way he can accelerate, and then stop on a dime and throw, gives his game another dimension that hasn't been seen before in the NFL.
Key To Defending It: Because he's left-handed, make Vick go to his right (the Bucs are good at this). And stop Warrick Dunn. If you can stop the run vs. the Falcons, you force them to run the offense solely through Vick. Relying so much on him means that Vick will be exhausted come the fourth quarter.

Key To Green Bay's Offense: The Packers rely on QB Brett Favre, but they have a balanced approach. They aren't especially fast on offense, but they look to RB Ahman Green for steady yardage and to Favre for leadership and key throws on third down.
Key To Defending It: Limit the Packers' running game. If you can put them into unfavorable second- and third-down situations, you have a better chance of forcing Favre into throwing some bad balls.

Key To New York Giants' Offense: TE Jeremy Shockey is the one matchup that opposing defenses have no matchup for -- he's faster than a safety and bigger than a cornerback. Shockey's effectiveness allows WR Amani Toomer to get one-on-one coverage, and RB Tiki Barber has run well all season. Surprisingly, the Giants have the total package on offense right now.
Key To Defending It: Find a defender -- probably a linebacker or safety -- who will accept the challenge of covering Shockey one-on-one. I wouldn't devote two defenders to him, because that would free up Toomer more. Let Shockey be the responsibility of one guy you have confidence in.

Key To Philadelphia's Offense: It depends on whether injured QB Donovan McNabb plays (broken ankle). With him, they're a totally different team, one of the NFL's best. The Eagles' role players have excelled in his absence, but he's still the key.
Key To Defending It: If McNabb is playing, focus on him -- and test his ankle. Play a Cover-2 zone, get some pressure on him and force him to be mobile. See if he can run coming off the injury. If McNabb isn't playing, focus on the run. Bring your safety up, play eight guys in the box and make the backup QB throw.

Key To San Francisco's Offense: WR Terrell Owens. Jeff Garcia-to-Owens is one of the NFL's most explosive tandems. With his size and speed, Owens presents matchup problems for any defense -- and he's confident that he can make plays in crunch time.
Key To Defending It: Limit Terrell's touches and his opportunities to get in the end zone. The best way to do this is to control the ball with your offense, by running the ball and keeping it away from the Niners.

Key To Tampa Bay's Offense: It depends on whether injured QB Brad Johnson plays (bruised lower back). The Bucs' offense depends on sharp timing between the quarterback and receivers. They look to complete quick passes in a West Coast scheme.
Key To Defending It: Prevent the receivers from gaining yards after the catch. The Bucs have been inconsistent with the run, so you don't need to focus on that. Just play fundamentally sound defense, cover well and tackle after the catch.