Divisional Matchups: Defense Is Crucial Packers at 49ers Saturday, 8 p.m., Fox Line: 49ers by 3 It is not true that San Francisco defensive end Justin Smith once raced a steam-powered hammer to dig a tunnel through a mountain using nothing but two hammers. He also did not carve the Grand Canyon by dragging his mighty ax. But in last season's divisional playoff game against New Orleans, he backed offensive tackle Jermon Bushrod into quarterback Drew Brees as if he were a tackling sled before forcing both opponents to the ground. For those keeping a tally, he tossed more than 500 pounds of humanity like a sack of flour. Smith's ability to pull off such feats of strength, and his importance in setting up the rest of the 49ers' defense, cannot be overstated. After he was forced to leave a Week 15 game against New England because an injured triceps, the vaunted 49ers defense fell apart. The Patriots nearly came back to win, and the next week Seattle crushed the 49ers. Even in a Week 17 win over Arizona, the defense allowed a touchdown pass by Brian Hoyer, which would have been unthinkable a few weeks earlier. Smith is expected to be back, but how effective he will be is unknown. A similar injury kept Ray Lewis out for 11 weeks. If the Cowboy, as his teammates call Smith, is ready to go, the 49ers' defense can shut down the Packers' offense and win at home. Without him, Aldon Smith is not nearly as effective at getting to the quarterback, and that puts a great deal of pressure on the cornerbacks, potentially San Francisco's weakest link. Giving Aaron Rodgers time to throw -- he will probably pick on cornerback Tarell Brown - could result in plenty of points for Green Bay. Colin Kaepernick, the 49ers' second-year quarterback, does not seem likely to keep up in a shootout with the league's reigning most valuable player. At least not yet. Ravens at Broncos Saturday, 4:30 p.m., CBS Line: Broncos by 10 Baltimore linebacker Ray Lewis, mostly known for tackling and dancing, showed off some solid football analysis when discussing this matchup. "He knows me very well; I know him very well," he told reporters about his relationship with Peyton Manning. But at the end of the day, it's not about me and me and Peyton. It's about their team against our team. Lewis, rumored to be closing in on a job analyzing football for ESPN next season, was right. But it is hard to believe that more than a few seconds of Saturday's broadcast will focus on anything other than him and Manning, two future Hall of Famers. Denver has been one of the season's most talked-about teams, and not just because of the improbable return of Manning from neck surgery to stardom. The Broncos' defense is intimidating, they have had a solid running game all season (even after losing Willis McGahee to injury), and they have won 11 consecutive games. The Ravens' season was not nearly as pretty. They missed Lewis and Terrell Suggs, last season's defensive player of the year, for large chunks of the season and gave up huge amounts of yardage each game, forcing their offense to carry far more of the load than in years past. Toward the end of the season, Baltimore's offense struggled as well, resulting in the dismissal of the unit's coordinator. Despite the drama, the Ravens are in the second-round of the postseason and have played well enough to make the 10-point spread a bit insulting, even if Denver is the right choice as a favorite. Pick: Broncos Seahawks at Falcons Line: Falcons by 1 In the 1979 cult classic movie "The Warriors," a gang from Coney Island finds itself on the run in the Bronx while the rest of the city's gangs pursue them. As solid as many believe the Coney Island crew to be, doing battle on enemy turf fills the journey with drama and the hope of returning home safely. The Seahawks cannot go home. The team known for raucous fans who make it nearly impossible for opposing offenses to hear plays called will try to win four consecutive playoff road games to take home the Vince Lombardi Trophy. Luckily for Seattle, as the season went on, the team's dependence on the home fans began to lessen. That coincided with the Seahawks' giving the rookie quarterback Russell Wilson more freedom in the offense. The combination of Wilson and Marshawn Lynch running the ball is devastating, and if opponents are not careful, Wilson can do quite a bit of damage throwing the ball as well. A fantastic Seattle defense will be without its best pass rusher, Chris Clemons, but still features the best secondary in the game and one of the few capable of shutting down Atlanta's Roddy White, Julio Jones and Tony Gonzalez. The Falcons, under the coordinator Mike Nolan, are not pushovers on defense. Despite far less attention, the unit matched the celebrated Seahawks with 31 takeaways, fifth in the N.F.L. But Seattle has the bearing of a team possessed, and Atlanta, continually forced to defend its previous playoff failures, does not. Texans at Patriots Sunday, 4:30 p.m., CBS Line: Patriots by 10 New England's offense is as balanced as it has ever been in the Tom Brady era. Brady was as effective as always, passing for 4,827 yards and 34 touchdowns this season, but the emergence of running back Stevan Ridley made the team nearly unstoppable. It is hard to believe that the Patriots, with Ridley and Danny Woodhead, among others, outrushed Houston and Arian Foster this season, averaging about 4 yards more a game on the ground. But the key to this game will be two New England defensive players: tackle Vince Wilfork and cornerback Aqib Talib. Wilfork can shut down Houston's one-cut running scheme by moving into the backfield on early downs; this season he also showed the ability to disrupt the pass. While Wilfork is wreaking havoc, Talib will be asked to make sure that Andre Johnson, Texans quarterback Matt Schaub's safety blanket, is not open downfield. Talib had a tumultuous season, including a suspension for violating the league's substance abuse policy (the second of his career) and a midseason trade from Tampa Bay. Now nursing a sore hip, he is crucial to shutting down Houston's offensive options. Even if Wilfork and Talib struggle, it is hard to imagine that Brady will have trouble scoring, even against a defense that played as well as Houston's did for much of this season. Pick: Patriots Times are Eastern. Picks do not reflect the betting line.