It’s hard to imagine a better football matchup than New England and San Diego. Both teams are balanced: strong on offense, defense, and special teams. The Patriots were a slightly better team over the second half of the season, but the Chargers were more consistent over the whole year and have the home-field advantage.

WHEN THE PATRIOTS HAVE THE BALL If the Patriots beat the Chargers on Sunday, they can thank the Jets. The reason has to do with New York’s midseason upset, not New England’s first-round playoff victory.

Back in Week 10, the Jets shut down the New England offense by blitzing Tom Brady relentlessly. In response, the Patriots altered their protection schemes, leaving more blockers and giving Brady more time to throw. That’s key against San Diego’s hellacious pass rush, particularly linebacker Shawne Merriman, who led the league with 17 sacks despite a fourgame suspension.

The Patriots receivers have been derided all year as a bunch of nonames, but if Brady has time to throw, he can usually find one of them open. Occasionally the Patriots will go deep, but most of their passing game consists of slowly marching down the field in chunks of seven or eight yards, augmented by handoffs to Corey Dillon and Laurence Maroney.

Watch for Brady to pick on cornerback Quentin Jammer; although he’s the best-known name in the San Diego secondary, both Drayton Florence and Antonio Cromartie played far better this season.

A look at the numbers during Merriman’s suspension shows just how important he is to the Chargers. With Merriman, San Diego was one of the top ten pass defenses. Without him, they were one of the 10 worst.

The Patriots should have no problem extending drives if they can get to third-and-short. They converted 82% of short-yardage situations, leading the NFL, while the Chargers stopped just 22% of these runs, which ranked 31st. Even a stop on third down won’t necessarily stop a drive, since the Patriots converted 16 of 19 opportunities on fourth down.

The Chargers also need to keep the Patriots out of the red zone, where the Patriots offense is second in DVOA and the Chargers defense ranks dead last. It’s more than just scoring touchdowns instead of field goals. Neither Brady nor the San Diego defense had any interceptions in the red zone.

WHEN THE CHARGERS HAVE THE BALL Excited Patriots fans often dismiss the NFL’s other teams as pretenders to the throne. But even the most obnoxious Boston sports radio caller has to acknowledge the greatness of the San Diego Chargers offense, led by MVP LaDainian Tomlinson and the best tight end in the league, Antonio Gates.

Young quarterbacks tend to struggle when they face a Bill Belichick defense for the first time, but Philip Rivers isn’t your average young quarterback. In his first year as San Diego’s starter, Rivers was one of the top quarterbacks in the league as well as one of the most consistent. He only had one really bad game, against Kansas City four weeks ago.

Belichick will surely attack Rivers with hard-to-decipher blitz schemes, but the most important battle along the line will be one of the most simple. Left tackle Marcus McNeill enjoyed an outstanding rookie year, but it will be hard for him to handle future Hall of Famer Richard Seymour without some assistance.

The San Diego running game does the most damage on runs to the side, since both Tomlinson and his backup Michael Turner are spectacular once they get into open space. Tomlinson’s long touchdowns aside, the blocking up the middle is actually average. If the Patriots can somehow get the Chargers to run right up into the teeth of their all-first round defensive line, they can contain Tomlinson (contain here being a relative term).

The Patriots don’t allow a lot of long touchdown runs. Until two weeks ago, the Patriots were leading the league in preventing double-digit runs for the fourth straight season. Maurice Jones-Drew’s “not down by contact” 74-yard touchdown in Week 16 changed that statistic, but it’s unlikely to be repeated by Tomlinson.

The one area where Tomlinson can really hurt New England is catching passes out of the backfield. That’s a problem for the Patriots defense and an area where Tomlinson excels.

Like the Chargers, the Patriots have a strong starting cornerback, Asante Samuel, and a week starting cornerback, Chad Scott. The Patriots often clamp down on the opposition’s top receiver, only to allow a huge game to the number two option. For the Chargers, that could mean a big day for big second-year receiver Vincent Jackson.

OUTLOOK If you can’t enjoy a game between two teams with this much talent, you probably should avoid watching football for the rest of your life. Home field makes San Diego a slight favorite, but either of these teams could easily be Super Bowl champion in three weeks.

Mr. Schatz is the editor in chief of FootballOutsiders.com.