Manning, Harrison will match wits

Times staff writer Lonnie White takes a look at the key matchup inside Sunday’s showdown at Indianapolis between the NFL’s only undefeated teams, the Colts and the New England Patriots:

There’s no denying that New England’s dynamic passing combination of Tom Brady and Randy Moss has dominated NFL highlights over the first half of the season.

Brady is on pace to break Peyton Manning’s single-season record for touchdown passes and Moss has already provided a year’s worth of spectacular plays in only eight games.

However, the key matchup to look out for in New England’s showdown against Indianapolis on Sunday will not involve Brady or Moss, or the Colts’ revamped defense.

No, the game-determining battle will feature Manning and his pre-snap line dance against the Patriots’ hybrid defense, which excels at switching from 3-4 to 4-3 alignments and confusing quarterbacks.

At this stage of Manning’s career, there’s nothing that he will do at the line of the scrimmage that should surprise New England, which has experienced his gyrates, flaps, points and stomps for years.

For a while, the Patriots had Manning’s number. New England won four in a row en route to winning three Super Bowls between 2002 to 2006. But Manning has had the upper hand lately in leading Indianapolis to three consecutive victories over the Patriots.

By now, New England understands that much of Manning’s exaggerated pre-snap moves and calls are bluffs. But the Patriots still have to determine which if any of those calls are real.

On Sunday, that main responsibility will often belong to veteran safety Rodney Harrison, who has gained a well-deserved reputation for out-thinking quarterbacks during line-of-scrimmage cat-and-mouse games.

Last season, Harrison sat out the AFC Championship game between these teams because of a knee injury, and his presence was dearly missed in the Colts’ 38-34 come-from-behind victory.

Indianapolis was able to erase an 18-point deficit thanks to several Manning completions over the middle of the field to tight end Dallas Clark, who finished with six catches for 137 yards.

Expect Harrison to be ready to deliver hits against this strategy on Sunday.

Since Harrison returned from an NFL suspension for HGH use earlier this season, he has provided a much-needed intimidating boost to the Patriots’ secondary. That will be an important factor against the Colts, who lose offensive steam when they struggle to complete passes inside the hash marks.

It has been years since Manning has had Indianapolis huddle between snaps and, over time, he’s mastered the 40-second play clock. Manning understands that every defense has a weakness and is always determined to figure out the soft spot before each play.

Whether that means making protection adjustments or route changes, Manning does everything he can to exploit matchup advantages that favor the Colts.

That brings us to Harrison, 34, who may have lost a step in coverage but is still a ferocious hitter with a high football IQ.

For Manning, the goal of the chess game will be to catch Harrison in man coverage as much as possible. The more times Harrison has to chase Clark down field, the more the Colts like their chances.

But Manning also has to be concerned about Harrison’s ability to anticipate plays. As the only player in NFL history to have at least 30 sacks and 30 interceptions in a career, Harrison gives the Patriots an edge because he can play the rush like a linebacker and still cover tight ends and backs.

Even when he’s wrong, Harrison can get an offense to switch to an ineffective play that might kill a promising drive.

Summary: Whether Harrison starts from the line of scrimmage or the defensive backfield, he has to be able to sneak inside the pocket to get to Manning for the Patriots’ zone blitz schemes to work.

If Harrison fails too often -- by getting blocked or guessing wrong -- look for the Colts to take full advantage with one big play after another.

lonnie.white@latimes.com