In November, the Colts met the Patriots in a close, hard-fought battle between two of the league’s top teams. The hype surrounding the game focused on quarterbacks Peyton Manning and Tom Brady, and the difference that night in New England was that Manning had a much better game than Brady did as Indianapolis won 27–20. But quarterback is only one position, and as the teams prepare to meet again in the AFC Championship Sunday, the other 45 players on each team deserve most of the attention.

WHEN THE PATRIOTS HAVE THE BALL Everyone who watched football this season thought the Colts run defense would be their downfall come playoff time. But through two playoff games, not only has the defense not hurt the Colts, it has come through and led them to victory against both the Kansas City Chiefs and the Baltimore Ravens. In two playoff games, the Colts have allowed just 127 yards on 37 runs.

A big reason is that safety Bob Sanders is finally healthy after playing just four games in the regular season. (The victory over the Patriots was one of the four. He led the Colts with eight tackles and intercepted Brady.) Defensive end Dwight Freeney, usually a threat against the pass but a liability against the run, has also played a part in the Colts’ playoff improvement by taking his pass rushing to the inside more often, so teams have a harder time running in his direction. And the Colts are lining up their defensive backs closer to the line of scrimmage to help in run support.

That last tactic is something both Kansas City and Baltimore failed to capitalize on. Now it’s New England’s turn. Look for Brady to pass to Reche Caldwell early and often. In their first meeting Caldwell, who led the Patriots in catches and yards this season, caught just one pass, but in general no. 1 receivers have burned the Colts’ secondary. Caldwell figures to have a big day Sunday — especially if Sanders and the rest of the secondary are focusing on the running game.

Whether Brady has time to pass will depend in large part on the battle between Freeney and Patriots left tackle Matt Light, which could be the most important individual match-up of the game. But that matchup won’t just be important on passing plays. The Patriots average 5.1 yards a carry running around the left end, the fourth-best average in the league, but they average 2.3 yards a carry running around the right end, dead last in the league. Those runs around the left end will look inviting if Freeney continues his recent habit of rushing to the inside.

New England’s rushing attack will come from veteran Corey Dillon and rookie Laurence Maroney. Both are effective runners, and the Colts’ success the last two weeks aside, it’s hard to envision Indianapolis shutting both of them down. Even counting the playoffs, the Colts have allowed 5.2 yards a carry this season, the worst in the league. To put that in perspective, 5.2 yards a carry was Jim Brown’s career average, which means the Colts have made the average runner look like the greatest runner in the history of the game.

The weak Colts defense is why Indianapolis had to win so many close games. Both teams won 12 games in the regular season, but only four of the Colts’ wins were by double-digit margins, while the Patriots had eight such wins. Counting the playoffs, the Patriots have outscored their opponents this season by a cumulative 446–264, while the Colts’ total score is 465–374.

With the exception of tackle Booger McFarland, who was brought in during the season to try to shore up the run defense, the Colts’ line is undersized, and New England’s offensive line should dominate in short-yardage situations. When they run on third or fourth down with a yard or two to go, the Patriots pick up the first down 82% of the time, the best average in the league. That helps explain why New England chooses to go for it so often on fourth down: The Patriots were an incredible 16-of-20 when going for it on fourth down this season. Expect that trend to continue Sunday, as the Colts allowed their opponents to pick up 11 first downs on 14 tries when going for it on fourth down. If the Patriots face a fourth-and-1, they’ll most likely go for it almost anywhere on the field — and a fourth down stop or conversion could be decisive.

WHEN THE COLTS HAVE THE BALL Patriots cornerback Asante Samuel is one of the best in the business, and he could be the next defensive back to give Manning fits in the playoffs. But Manning might just avoid Samuel entirely. Manning is at his best when he looks to exploit weaknesses in the secondary, and the Patriots secondary has some holes. Although New England can shut down the other team’s top receiver, the Patriots’ defensive scheme devotes so much attention to first receivers that the opponent’s second receiver usually plays well against New England. Manning usually distributes the ball evenly between his two favorite targets, Marvin Harrison and Reggie Wayne, but on Sunday he’ll focus primarily on whichever receiver is on the other side of the field, away from Samuel.

Safety Rodney Harrison has missed New England’s two playoff games with a sprained knee, and it’s unclear whether he’ll play Sunday. Harrison is tough and physical and knows how to knock opposing receivers around while (usually) avoiding penalties for pass interference and illegal contact. That makes him exactly the kind of defensive back the Colts hate to face. His presence would make a big difference for New England — and his absence would be a major confidence boost for Manning.

The Colts split their carries between two running backs, and throughout the regular season, rookie Joseph Addai was a significantly better runner than veteran Dominic Rhodes. But Rhodes has played well in the playoffs, especially on the Colts’ final drive against Baltimore, when Indianapolis took more than seven minutes off the clock by giving Rhodes the ball 11 times. Addai is the faster runner of the two, but Rhodes has more power. Expect the Colts to split the workload between the two of them equally.

When teams run against the Patriots, they usually go right up the gut — 68% of runs against New England went up the middle this season, which is the highest rate in the league. The Colts run well up the middle, but if they try it against the Patriots, center Jeff Saturday will have a tough assignment against nose tackle Vince Wilfork.

Left tackle Tarik Glenn is the Colts’ best lineman. The Colts average an NFL-best 5.6 yards a carry running behind the left tackle and 4.6 yards per carry running around the left end, but they average just 4.4 yards a carry running behind the right tackle and 3.6 yards per carry running around the right end. Glenn will have a big challenge going against New England’s Richard Seymour. Seymour was the only Patriot selected to the Pro Bowl and is one of the league’s best defensive lineman, although he struggled on Sunday against San Diego left tackle Marcus McNeill.

SPECIAL TEAMS If Manning and co. can get into field goal range, they’ll feel comfortable with their kicker. By signing Adam Vinatieri away from the Patriots, the Colts added field goal accuracy and playoff experience to their roster. Vinatieri is 7-for-7 in the Colts’ two playoff games.

Field goals, however, are the only area where the Colts have the special teams advantage. Stephen Gostkowski, the rookie the Patriots drafted to replace Vinatieri, has more leg strength than Vinatieri on kickoffs, the Patriots’ coverage units are better than the Colts’, and New England has significantly better return men than Indianapolis.

OUTLOOK The NFL hype machine would say otherwise, but this game may turn out to be less about which quarterback plays better, Manning or Brady, than about which safety is healthier, Sanders or Harrison. Sanders looks like he’s back to full speed, while Harrison is doubtful. Combine that with the home-field advantage the Colts earned by winning at New England in November, and Indianapolis is the favorite to win what promises to be a great game between two great teams.

Mr. Smith is a writer for FootballOutsiders.com.