t's easy to oversimplify the matchup between the Colts offense and the Bears defense as irresistible force versus immovable object.

By any measure, the Colts offense is great, arguably the best in football for the last five years. Over the past two seasons, the Bears defense has been one of the best in the NFL. The stars come out when these units are on the field: Peyton Manning, Reggie Wayne and Marvin Harrison for the Colts, Brian Urlacher and Lance Briggs for the Bears.

But the Colts offense has its weaknesses, as does the Bears defense. And each team is well-suited to attack their opponent's soft spot. The Bears will attempt to physically dominate the Colts offensive line, while the Colts will use spread formations, audibles, and their no-huddle offense to tire the Bears pass rush and force errors by their defensive backs.

WHEN THE COLTS RUN

The Colts base alignment is a single-back formation with split wideouts and tight end Dallas Clark acting as a slot receiver. This formation lends itself to a handful of basic running plays, including stretches, draws, and delays. When the Colts run the ball, they are usually executing one of these plays.

On a stretch run (a play the Colts execute constantly), the offensive linemen slant hard in one direction at the snap, bringing the defensive line with them. The goal is to create space for cutbacks by forcing defensive linemen and linebackers to move laterally. The Colts offensive line is well-suited for this type of run. None of their linemen is an overpowering in-line blocker: the Colts line was built for pass protection, and they are better at sustaining blocks and walling off defenders than they are at driving them backwards.

When the Colts execute a stretch left, they work very hard on the backside of the play to create a cutback lane. Left tackle Tarik Glenn and tight end Bryan Fletcher excel at sealing off the backside of a run, and both Joseph Addai and Dominic Rhodes have the vision and quickness to cut against the grain and pick up significant yardage. Addai and Rhodes also move the chains by cutting inside behind the blocking of center Jeff Saturday, the Colts' best lineman. Defenders must flow along the line to bottle up these stretch runs, but if they over-pursue the Colts will punish them.

The Colts running game is built to complement and support their passing attack, so delays and draws are a big part of their typical gameplan. When the Colts are in their hurry-up offense, they'll use shotgun draw plays to Addai or Rhodes to keep opposing linebackers and safeties from blitzing or dropping immediately into coverage. Both of the Colts backs are good at bursting through the line of scrimmage, making a cut, and then taking what the defense offers. Manning and the Colts linemen disguise draw plays well, so defenders can't sniff out running plays by reading cues from the offensive line.

The Bears will slow the Colts running game by using more five-man fronts than the Colts typically see. Most teams keep their linebackers deep when facing the Colts, but Lovie Smith will often place Hunter Hillenmeyer at the line of scrimmage, typically over tight end Fletcher. The presence of an extra linebacker will help seal the back side and will limit the amount of combo blocking the Colts can do on stretch runs. The Bears linebackers are exceptional at play diagnosis and will be able to avoid blocks and shoot gaps when they read run, so Manning can't expect Hillenmeyer, Briggs, and Urlacher to play back on their heels the way many opponents do. Offensive coordinator Tom Moore may scheme to clear linebackers out of the box by using more spread formations or multi-receiver packages.

WHEN THE COLTS PASS

After the performance against the Patriots, it's hard to imagine many people still having doubts about Manning, the quarterback who already owns several NFL passing records and will own many more before he's done, and who now has won the Big Game some said he couldn't. But what about Marvin Harrison, Manning's favorite receiver throughout his career?

When Harrison caught his 1,000th career pass this season, Manning called him the best teammate he's ever had. But Harrison has dropped some of Manning's best passes in these playoffs, and the only times Manning looked bad against New England were on the plays when he looked like he was forcing the ball to Harrison. With just 10 catches for 134 yards in three playoff games, Harrison hasn't been a particularly important part of the Colts' offense. Maybe, at 34-years-old, Harrison is finally on the decline.

Tight end Dallas Clark has more than made up for Harrison's problems, though. Clark is the Colts' leading receiver in catches (17) yards (281) and yards per catch (16.5) in this year's playoffs. Clark is listed as a tight end, but the Colts really use him more like a slot receiver — the true tight ends are Fletcher and Ben Utecht, both of whom are just role players in the passing game.

Few linebackers can cover Clark when he runs over the middle, and when Clark finds himself one-on-one with a linebacker, Manning usually takes advantage of the mismatch. There's just one problem against the Bears, though: Clark against the Bears' linebackers won't be a mismatch. Urlacher and Briggs are two of the best coverage linebackers in the league, and Clark can't outrun them the way he outran New England's linebackers in the AFC Championship.

Although Reggie Bush had a big day against them, the Bears' linebackers have also been excellent in coverage on running backs for most of the season. Manning likes to get both Addai and Rhodes involved in the passing game, but with the way Urlacher drills running backs who try to run routes over the middle, he'd be advised to use his running backs only as a last resort.

That means if Manning is looking for a mismatch, he might be best served looking to wide receiver Reggie Wayne. Bears coach Lovie Smith doesn't believe in adjusting his coverage for any one wide receiver, a philosophy that certainly has its advantages — Chicago cornerbacks Nathan Vasher and Charles Tillman know going into the game exactly what they need to do and won't be bogged down by in-game adjustments — but also has some disadvantages.

Those disadvantages were seen most clearly in last year's playoff loss to the Carolina Panthers, when receiver Steve Smith was simply too quick for Chicago's secondary, and the Bears never changed anything to give their cornerbacks (usually Tillman) help with him. Wayne is the fastest of the Colts' receivers, and if they don't have a better answer for Wayne this year than they had for Smith last year, it'll be a long day for Chicago.

Much like Dan Marino, Manning delivers the ball so quickly that it is nearly impossible to sack him, and when teams blitz he usually delivers the ball to his hot read and makes them pay. But the Bears have some interesting wrinkles that might give Manning problems. Smith and defensive coordinator Ron Rivera have three speedy defensive ends in Alex Brown, Adewale Ogunleye and Mark Anderson, and they like to take advantage of that speed by dropping their defensive ends into coverage.

Quarterbacks are hard-wired to expect the defensive ends to rush directly at them, and when the ends instead drop into coverage, it frustrates them. Chicago likes to run an overload blitz with Briggs blitzing and the defensive end dropping into coverage in the flat in Briggs' place. That's a hard scheme for a quarterback to get accustomed to, even a quarterback who does as much film study as Manning.

We'll hear a lot this week about how closely Smith and Tony Dungy have worked together, but we won't hear much about whether that will affect either team. Here's one way it could: The head coach who better prepares his own quarterback for the defense he'll face will be the one who comes out ahead. It's hard to say who will do a better job preparing his quarterback, Smith or Dungy, but it's not hard to say which quarterback seems more ready to absorb those lessons. Manning's presence gives the Colts a decided edge.