San Francisco came back to secure a thrilling 41-34 victory at New England after squandering a 28-point lead to confirm their place in the post-season action.
NFL: Showdown Sunday joy for 49ers and Green Bay as they secure play-off spots
Green Bay and Baltimore and the San Francisco 49ers all secured playoff berths while the Dallas Cowboys boosted their postseason chances on "Showdown Sunday".
Six matchups of NFL clubs with winning records prompted the extra attention to the third-to-last week of the season.
Never before had so many games between teams with winning records been staged on the same day so late in a campaign.
Brandon Carr intercepted Ben Roethlisberger's pass in overtime and Dan Bailey kicked the winning field goal moments later as the Dallas Cowboys edged out the Pittsburgh Steelers 27-24.
Carr returned the interception for 36 yards to the one-yard line before Bailey booted a game-winning kick for the second straight win.
"I just broke for the ball and waited for it to come my way," Carr said.
"I saw it clear as day. I jumped for the ball, went with my instincts and got it."
The victory moves the Cowboys, 8-6, into a three-way tie at the top of the NFC East alongside the New York Giants and Washington Redskins, while the slumping Steelers lost for the fourth time in five outings.
All NFL contests observed a pregame moment of silence in tribute to the 26 people, 20 of them children, who were killed Friday by a gunman at a school in Newtown, Connecticut.
New York Giants players wore helmet decals with the initials "SHES" for Sandy Hook Elementary School, where the tragedy took place.
The Giants suffered their fourth loss in six games when host Atlanta blanked New York 34-0. Matt Ryan threw three touchdown passes, two to Julio Jones, and the Falcons' defence imposed the first shutout on the Giants since 1996.
New York fell to 8-6 with the loss, allowing Dallas and Washington to match the Giants atop the NFC East division with two weeks remaining in the season.
Kirk Cousins, making his first NFL start as a fill-in for injured fellow rookie Robert Griffin III, threw for 329 yards and two touchdowns to spark Washington to a fifth consecutive victory with a 38-21 triumph at Cleveland.
The Redskins are on their longest win streak since 2005.
"The coaches had a great game plan," Cousins said.
"They kept it simple and put me in situations that allowed me to be successful."
Quarterback Russell Wilson threw his hat into the ring for NFL rookie of year honours, rushing for three touchdowns and passing for another as the Seattle Seahawks whipped the Buffalo Bills 50-17 on Sunday to close in on a playoff spot.
Coming off a 58-0 blowout of the Arizona Cardinals, the Seahawks (9-5) again flexed their offensive muscles by notching their fifth win in six games to set the pace in the NFC wild card race and keep the pressure on the San Francisco 49ers for top spot in the NFC West division.
Taken in the third round of the draft with the 75th pick, Wilson has outshone his more celebrated rookie rivals the last two weeks as the Seahawks outscored opponents 108-17 to become just the third team to score 50 or more points in consecutive games.
"I believe it hasn't happened (scoring 50 points in consecutive weeks) since 1950, that's tough to do, that's playing great football, that's playing efficient football," Russell told reporters. "Our offence is really explosive right now, we do so many multiple things to attack the defence in terms of throwing the ball, in terms of running and in terms of a couple trick plays here and there and it's hard to stop."
Green Bay's Aaron Rodgers completed 23-of-26 passes for 291 yards and three touchdowns, all to James Jones, and the visiting Packers downed their arch rivals to seal a playoff trip.
The Packers, 10-4, have lost only once in their past nine games while the Bears fell to 8-6 with their third loss in a row and fifth in six games.
Matt Schaub completed 23-of-31 passes for 261 yards and a touchdown and Arian Foster ran 27 times for 165 yards to power host Houston over Indianapolis 29-17, clinching the AFC South title for the 12-2 Texans.
The Colts fell to 9-5 but remain in position for a wild-card playoff spot.
Peyton Manning completed 17-of-28 passes for 204 yards and a touchdown to spark the Denver Broncos to their ninth victory in a row, a 34-17 romp at Baltimore.
The AFC West champion Broncos, 11-3, have not won so many consecutive games since taking 13 in a row in 1998 on the way to a Super Bowl title.
It was the third loss in a row for the Ravens, who fell to 9-5 and remain only one game ahead of Cincinnati in the AFC North.
Adrian Peterson ran 24 times for 212 yards and a touchdown to lead Minnesota over host St. Louis 36-22 and into the NFC playoff hunt at 8-6.
Peterson's 1,812 rushing yards this year are 293 shy of Eric Dickerson's one-season NFL record with two games to play.
Drew Brees completed 26-of-39 passes for 307 yards and four touchdowns to lead host New Orleans over Tampa Bay 41-0, leaving both teams 6-8. Miami rose to 6-8 with a 24-3 home rout of Jacksonville.
Arizona snapped a nine-game losing streak with a 38-10 home rout of Detroit while Carolina ripped host San Diego 31-7 and Oakland blanked visiting Kansas City 15-0.
The San Francisco 49ers squandered a 28-point lead against an explosive New England Patriots on Sunday but recovered late on to secure a playoffs berth with a thrilling 41-34 road victory.
The 49ers dominated early in rainy New England, racing to a 31-3 advantage in the third quarter but Tom Brady and his top-ranked Patriots offence caught fire with 28 unanswered points to tie the game with a little under seven minutes remaining.
San Francisco's second-year quarterback Colin Kaepernick responded seconds later with a 38-yard touchdown pass to Michael Crabtree, his fourth TD throw of the game, to put the 49ers (10-3-1) back in front for good.
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