The Cardinals are playing for the playoffs but key injuries could derail their chances against division rival Seattle, winners of four straight. The Steelers have all but wrapped up the AFC North, but have an opportunity to upend the undefeated Patriots and get one step closer to a first-round playoff bye in the process.

CARDINALS (6–6) at SEAHAWKS (8–4)
Sunday, 4:05 p.m.

The Cardinals staved off a last-second Hail Mary to beat the Browns last Sunday. That, coupled with the Lions’ fourth consecutive loss, moves Arizona into the final wild-card spot. The NFC West matchup against the division leading Seahawks will be the Cardinals’ most important game of the season.

Unfortunately, Arizona will likely be without its two starting wide receivers. Larry Fitzgerald is nursing a groin injury and won’t play this weekend. Anquan Boldin had to be helped off the field against the Browns after dislocating his toe. If quarterback Kurt Warner is without his two primary targets, Bryant Johnson and tight end Leonard Pope could be busy, with running back J.J. Arrington possibly getting more involved in the passing game.

Complicating matters is the Seahawks’ defense, which has registered 14 sacks in the last month. In the first meeting between these teams, Seattle just missed sacking then-quarterback Matt Leinart on several occasions because of his ability to get rid of the ball quickly. Warner’s gone down nine times in his last four starts, but wasn’t sacked against the Browns.

After trying to fit a square peg in a round hole, Seattle head coach Mike Holmgren has all but abandoned the running game and is putting his offense on the shoulders of quarterback Matt Hasselbeck. So far, so good: The Seahawks have won four in a row, and over that time, Hasselbeck is completing 62% of his passes, averaging 263 yards a game, and nearly two touchdowns. Running back Maurice Morris averaged just 17 rushes over that span, but sported a healthy 4.7-yard average.

Shaun Alexander returned from injury last week and got the bulk of the carries, but Holmgren wants to keep Morris involved, which means the backs will split the carries.

The Cardinals beat the Seahawks back in Week 2, but if this game comes down to penalties, look for Seattle to have the edge: Through Week 13, Arizona led the NFL in penalties with 123. Seattle had the league’s fewest with 51.

STEELERS (9–3) at PATRIOTS (12–0)
Sunday, 4:15 p.m.

The Patriots are 4–1 against the Steelers in the Bill Belichick era, including two AFC Championship victories, in 2001 and 2004. With both teams leading their respective divisions, Sunday’s contest doesn’t carry the import of a post-season game, but it could foreshadow an AFC Division matchup, depending on how the playoff seedings shake out.

In the meantime, New England is coming off its second straight mediocre performance, eking out back-to-back three-point victories after winning its first 10 games by an average margin of 25 points. Against the Eagles two weeks ago, the Patriots’ pass defense was exposed while the offense looked as potent as ever. Last Monday versus the Ravens, it was the run defense that was made to look vulnerable. And the offense had its worse effort of the season; quarterback Tom Brady completed less than half of his passes and was harassed most of the game by Baltimore’s unrelenting pass rush.

Like the Ravens, the Steelers feature a blitz-happy defense. Earlier this season, against the pass-oriented offenses of Seattle and Cincinnati, Pittsburgh eschewed the blitz and rushed just three players while dropping eight into coverage. The Steelers were 3-0 in those games, allowing just 17 points, but Brady is completing more than 70% of his throws, and when given time to set up in the pocket he has methodically picked apart defenses.

Both the Eagles and the Ravens risked giving up the big play to put pressure on Brady. The results: In those two games, Brady was sacked six times, completed 57% of his passes, and he tossed just three touchdowns (prior to Week 12, Brady had thrown at least three touchdowns in every game). If the Steelers are to have a chance, they will need to force Brady into getting rid of the ball before he is ready.

Pittsburgh, long described as a power-running team, has evolved into a more balanced offense with Jerome Bettis’s retirement after the 2005 season, and quarterback Ben Roethlisberger’s maturation. They will need to rush the ball effectively against the Patriots to control the clock and keep Brady off the field. For the Steelers to rely on the ground game requires its defense to bottle up New England’s offense, which, to date, has proven virtually impossible.

Mr. Wilson is a writer for FootballOutsiders.com.