The Indianapolis Colts defense is almost as lopsided as its offense.  It has been effective against the pass, but they can be run against.  I would suspect that it has something to do with the size of their defensive line; they have a smaller line, but as the link posted by 'Shake and Bake' shows they can be effective.  Their front four weigh in at 1064 lbs total.  While the Chargers have had their troubles running the ball, with LT healthy I would expect this should be a line that our offensive line should be able to wear on.  A running game would also burn clock; the more the Chargers can keep the ball out of Peyton's hands, the less exposed our secondary will be.  Here are the numbers for the Colts defense:

At just 181 yards a game, the Colts have been effective against the pass.  Football Outsiders ranks them just about dead average against the pass and run; so some of these stats may be the result of facing good running attacks.  Outsiders also ranks the Colts reasonably well covering the primary receivers, third receivers and running backs catching the ball seems to be weaker.  Dwight Freeney at right defensive end brings the most heat on the pass rush, he has 7 sacks this season.  Robert Mathis on the left has 5; the Chargers will need to slow them down to give Rivers time to find to throw.

Bob Sanders does an amazing job for the Colts at Strong Safety; this week he has been missing practice with a swollen knee.  It's hard to tell how serious it is, but he has missed practice Weds & Thursday.  Their other Safety is Melvin Bullitt and he missed Wednesday practice with an illness, but I would be surprised if he didn't play Sunday.  Bullitt has four interceptions on the year; the Colts secondary has a total of ten picks on the season.  Tim Jennings is the right cornerback, and at 5'8" he may get picked on against our taller receivers; he has had some bad games getting burned with catches and penalties. 

One final factor to consider is special teams.  Last year in the regular season Darren Sproles returned a kickoff and a punt for TDs; how well Indianapolis covers could be a factor in the game.  Their punter is averaging 45 yards per kick with a 38 yard average; in comparison Scifres is averaging 48 yards, with a 43 yard net; but there may not be a lot of punting this Sunday.  In Vinitari and Kaeding you have two of the most accurate field goal kickers in the NFL; Kaeding is coming off the huge miss at Pittsburgh however.  San Diego's return game seems to be the most likely to play a role in the game.  Overall this game has the makings of a shootout; it may come down to who has the ball last in the fourth quarter; lets hope it's the Chargers.