The 2011 NFL season has been unpredictable thus far. After three weeks, a team that missed the playoffs in 2010 is at the top, or tied for the lead, in every division in both the AFC and NFC. Week Four brings new tests for the three undefeated teams in Detroit, Buffalo and Green Bay and new opportunities for those squads looking for their first wins.

Here’s a preview of each game:

NFL schedule for Sunday, Oct. 2

Detroit Lions at Dallas Cowboys – 1:00 PM

The Lions’ tandem of quarterback Matthew Stafford and receiver Calvin Johnson leads unbeaten Detroit (3-0) into Dallas (2-1) to face a Cowboys defense that forced Redskins quarterback Rex Grossman into two key turnovers Monday night. Stafford has thrown only two interceptions to his nine passing touchdowns in 2011. Detroit hopes to register hits on Dallas quarterback Tony Romo, who is still nursing cracked ribs. Romo has steered the Cowboys to two comeback wins in a row, but the Lions defense has allowed both the fewest points and passing yards in the NFC.

Carolina Panthers at Chicago Bears – 1:00 PM

After getting his first NFL win despite his worst individual statistics of the season, Carolina rookie quarterback Cam Newton hopes to make it two-in-a-row for the Panthers (1-2) against Chicago (1-2). The Bears defense, which was led by current Panthers head coach Ron Rivera as defensive coordinator from 2004-06, wants to force Newton into mistakes and take pressure off the Chicago offense, which has sputtered since the first week of the season. Chicago offensive coordinator Mike Martz must get better offensive balance; the Bears rank 31st in the NFL in rushing with 53.7 yards per game. Running back Matt Forte can help. He had a career-high 166 yards against Carolina in the Bears 23-6 win last season.

Buffalo Bills at Cincinnati Bengals – 1:00 PM

Averaging 37.7 points per game, Buffalo (3-0) rolls into Cincinnati with the NFL’s highest scoring offense. The Bengals (1-2) must find a way to stop both Bills quarterback Ryan Fitzpatrick, with nine passing touchdowns, and running back Fred Jackson, who ranks fourth in the NFL with 303 yards rushing. The Cincinnati run defense matches up well, allowing just 2.9 yards per rush. Bengals rookie quarterback Andy Dalton needs to play better than he did last week. His 40.8 passer rating helped keep Cincinnati from reaching the end zone against the 49ers. Dalton will have opportunities against a Bills defense that has yielded plenty of points, but has yet to lose.

Tennessee Titans at Cleveland Browns – 1:00 PM

After missing last week’s game with strep throat, power back Peyton Hillis may return for Cleveland (2-1). Hillis and Montario Hardesty will help Browns quarterback Colt McCoy try to score against Tennessee (2-1), whose defense has allowed the second fewest points per game in the NFL (14.3). The Titans hope to see their own, once-powerful running game return. Titans running back Chris Johnson has only 98 yards rushing this year. With wide receiver Kenny Britt lost for the season after tearing two ligaments in his knee last week, Tennessee needs offense from someone other than quarterback Matt Hasselbeck, who has thrown for 932 yards – good for eighth in the NFL.

Minnesota Vikings at Kansas City Chiefs – 1:00 PM

Minnesota (0-3) has given up three second-half leads in three weeks in 2011. Despite the league’s third best rushing attack, led by Adrian Peterson’s 98.7 yards per game, the Vikings haven’t been able to finish off teams. Kansas City (0-3) hasn’t been able to mount much offense against anyone. The Chiefs had only 34 total yards in the first half against San Diego last week and did not pick up a first down until the second half. Chiefs coach Todd Haley must get running backs Dexter McCluster and Thomas Jones going against a Minnesota run defense that is fourth best in the league.

Washington Redskins at St. Louis Rams – 1:00 PM

St. Louis (0-3) has been outscored by 60 points in its three losses. The Rams need running back Steven Jackson to run well and alleviate pressure that Washington (2-1) is sure to bring against second-year quarterback Sam Bradford, who has been sacked 11 times this year. The Redskins defense has forced six fumbles, tied for second most in the league. Washington should be able to move the ball against the St. Louis defense, which has given up the second-most yards per game in the league (426.3). Redskins’ receivers Santana Moss and Jabar Gaffney may help extend the Rams defense.

New Orleans Saints at Jacksonville Jaguars – 1:00 PM

New Orleans (2-1) welcomes receiver Marques Colston back from injury to an offense that has averaged 34.7 points per game without him. Jacksonville (1-2) hopes its defense is up to the challenge that Saints quarterback Drew Brees presents. Getting the Jaguars offense to control the ball and keep Brees off the field would help. Jacksonville running back Maurice Jones-Drew has run for 307 yards, third-best in the NFL, but the Jaguars have scored just 29 points in three weeks.  Even if the Jaguars do limit Brees and company to less than five scores, they’ll need rookie quarterback Blaine Gabbert to play very well to win. He had only 139 passing yards in his first NFL start last week.

Pittsburgh Steelers at Houston Texans – 1:00 PM

Houston (2-1) gets 2010 NFL rushing champ Arian Foster back from a hamstring injury just in time to run him into the fierce defense of Pittsburgh (2-1). The Steelers have the best run defense in the NFL over the span of the last ten years. They will make it tough on Foster and Texans quarterback Matt Schaub, who has 823 yards passing this season. Speedy Pittsburgh wide receiver Mike Wallace will look to extend his consecutive 100-yard receiving games to seven, which would tie an NFL record. He’ll be pitted against a Houston secondary that New Orleans victimized for 23 fourth quarter points last week.

San Francisco 49ers at Philadelphia Eagles – 1:00 PM

Quarterback Michael Vick said he will play for Philadelphia (1-2) this week against San Francisco (2-1), but will he finish the game? Vick hasn’t done so in two weeks, suffering a bruised right hand against  the N.Y. Giants and a concussion against Atlanta. Philadelphia would do well to use running back LeSean McCoy, who is second in the NFL with 345 rushing yards. He leads all running backs with five touchdowns. San Francisco has allowed just 62.7 rushing yards per game, third-best in the NFL, so they may force the Eagles to pass. The 49ers offense may lean heavily on tight end Vernon Davis and running back Frank Gore, who has a sprained ankle. Both players create match-up problems for the Philadelphia defense, which has given up 64 points over the last two games.

New York Giants at Arizona Cardinals – 4:05 PM

Arizona (1-2) was unable to generate enough offense in last week’s 13-10 loss against Seattle. With the New York Giants (2-1) getting back Pro Bowl defensive end Osi Umenyiora to add to already effective linemen Jason Pierre-Paul and Justin Tuck, Cardinals quarterback Kevin Kolb could be in for another difficult day. Kolb threw two interceptions last week. The Giants are the best in the league in red-zone touchdown efficiency, but quarterback Eli Manning will have to continue that production against a Cardinals defense that is fourth in the NFC in points allowed.

Atlanta Falcons at Seattle Seahawks – 4:05 PM

For Atlanta (1-2) to get back above.500, it must start allowing quarterback Matt Ryan a chance to throw the ball without being pressured. Ryan has been sacked 13 times in 2011, while the Falcons offense has  been awful in the team’s two losses. If running back Michael Turner can carve into the Seattle defense, the Falcons should be able to control the game. Seattle (1-2) wants to build on its first win of the season last week by establishing a more consistent offense behind quarterback Tarvaris Jackson and Sidney Rice at wide receiver. Atlanta’s 22nd-ranked pass defense is vulnerable.

Miami Dolphins at San Diego Chargers – 4:15 PM

Miami coach Tony Sparano may need this win more than the Dolphins (0-3). Miami is 30th in total defense and its offense has slowed after a big first week. Miami needs quarterback Chad Henne to complete more than 56.5 percent of his passes. San Diego (2-1) must hope that this isn’t the week that Chargers quarterback Philip Rivers’ interceptions catch up with him. The league-worst six picks thrown by Rivers have been offset by his 979 passing yards and a rushing attack led by Chargers’ Ryan Mathews, who has 207 yards gained.

New England Patriots at Oakland Raiders – 4:15 PM

Oakland (2-1) is most successful when it runs the ball behind Darren McFadden, the NFL’s leading rusher with 131 yards per game. The Raiders hope to pile up yards on the shaky New England (2-1) defense, which is giving up 468 yards per game.  Oakland needs McFadden and quarterback Jason Campbell to control the ball and keep it away from Patriots quarterback Tom Brady. The league’s  leading passer, Brady already has 1327 yards and 11 touchdowns. He will test the Raiders defense, who will look to hit him often.

Denver Broncos at Green Bay Packers – 4:15 PM

Green Bay (3-0) will turn quarterback Aaron Rodgers and tight end Jermichael Finley loose on Denver (1-2), whose defense is better against the run than the pass. The Packers want to create a pressure offense to wear down Denver, while using its NFL-best rushing defense to force Broncos quarterback Kyle Orton into making plays. Orton’s play has been inconsistent and he’ll need help from running back Knowshon Moreno, who should return from a hamstring injury, to give Denver a chance to pull the upset.

New York Jets at Baltimore Ravens – 8:20 PM

In what may be the most physical game of the day, the Jets (2-1) will look to get back to winning behind coach Rex Ryan, who was a defensive coach for 10 years in Baltimore. The defenses he helped build for the Ravens may be better than his current squad, which is allowing 136.7 rushing yards per game. Baltimore (2-1) may use running back Ray Rice to set up its passing game, led by quarterback Joe Flacco. Jets quarterback Mark Sanchez is expected to start despite suffering a broken nose against the Raiders last week. Center Nick Mangold may be out once again for the Jets, creating a dangerous weakness in the offensive line for the Ravens aggressive defense.

NFL schedule for Monday, October 3

Indianapolis at Tampa Bay – 8:30 PM

With quarterback Kerry Collins still groggy from hits suffered last Sunday night against Pittsburgh, Indianapolis (0-3) may start backup Curtis Painter against Tampa Bay (2-1) on Monday night. Neither player figures to approximate the void created by the continued absence of Colts star quarterback Peyton Manning, who is out indefinitely with a neck injury. The Colts best hope is that running back Joseph Addai leads time-consuming drives, and whoever is at quarterback doesn’t turn the ball over to the opportunistic Buccaneer defense of coach Raheem Morris. Tampa Bay quarterback Josh Freeman is a winner, but he does have six turnovers this year. The Colts need to force more of them.