Which Seahawks defense will show up on Sunday?

The contest will begin before Peyton Manning snaps the ball.

It will start with a staredown between the Colts quarterback known for his efficiency and a Seahawks defense that has shown inconsistency this year.

Manning will scan the field, digest the formation and commence with a series of hand signs generally reserved for third-base coaches and games of charades. Seattle's defense will camouflage its coverage as long as it can, trying to hide its true colors from the quarterback with computer-quick processing. It's a test of wills safety Deon Grant is looking forward to.

"I love facing a challenge," said Grant, one of the Seahawks' defensive captains. "And I know for a fact that facing him is going to be one of the biggest challenges you can face."

So what will Manning see today when he stares across the line of scrimmage?

Will it be the defense that gave the Seahawks a fourth-quarter lead last week against the Bears after three quarters of miscues and missed field goals? Or will it be the defense that performed like it was on roller skates in the final five minutes, pushed backward without much trouble on Chicago's game-winning touchdown drive?

Will it be the defense that shut out St. Louis in the season opener despite three first-quarter turnovers by Seattle's offense, or the unit that gave up two touchdown runs of 79 yards or more to San Francisco's Frank Gore?

Not much is expected this weekend of the Seahawks, who are 1-2 and a double-digit underdog. They've lost nine of their past 11 regular-season games, and they're almost certain to start backup quarterback Seneca Wallace, with Matt Hasselbeck nursing a broken rib. If Seattle is going to be the first team to beat Indianapolis this season, it will depend on the defense's ability to disrupt Manning.

There are signs that the Seahawks just might have a pretty good defense. They are 11th in the league in yards allowed, but that isn't quite as good an indicator as first downs allowed and third-down percentage, which show a team's ability to squelch drives. The Seahawks are in the top five in each category, and this week middle linebacker Lofa Tatupu is expected to start and cornerback Josh Wilson might also be available.

But Seattle has so far faced St. Louis, San Francisco and Chicago, which might boast the three least formidable groups of receivers in the league. Indianapolis might not have Marvin Harrison anymore, but Reggie Wayne is leading the league in receiving yardage (325) and tight end Dallas Clark has seven third-down catches, more than all but one player in the AFC.

Indianapolis' offense is so potent, the Colts won in Miami two weeks ago despite having the ball for only about one-quarter of the game.

Manning is the motor of the offense, as well as rudder that determines direction and the keel that keeps everything upright. The Colts do not use that many different personnel groups, just two or three every week. They trust their quarterback's ability to decipher the defense and react.

Can Seattle include enough innovations to throw Manning off balance without exposing a weakness that he will inevitably find?

"If you don't know exactly what you're doing, he's going find you," Seahawks coach Jim Mora said. "But at the same time, you've got to make him figure it out a little bit."

That will start at the line of scrimmage today. What Manning sees will go a long way toward deciding this game.

Danny O'Neil: 206-464-2364 or doneil@seattletimes.com