The Carolina Panthers, New England Patriots and Cincinnati Bengals all clinched playoff spots as the NFL playoff picture came into sharper focus on Sunday.
In the AFC, the post-season puzzle is nearly complete with the Patriots, Bengals, Denver Broncos and Indianapolis Colts all confirmed as division champions and the Kansas City Chiefs having also secured a playoff berth.
With just one week remaining on the regular season schedule, the Miami Dolphins (8-7), Baltimore Ravens (8-7), San Diego Chargers (8-7) and Pittsburgh Steelers (7-8) will battle for the AFC's final wildcard spot.
Things are not as clear in the NFC, where all four division crowns were still up for grabs and only the Seahawks and Panthers had locked up playoff positions.
Before the day is over, however, the NFC could yet crown one unlikely division champion. The Chicago Bears (8-6) were in position to clinch the North title with a win over the Philadelphia Eagles in the nightcap after the playoff hopes of the Detroit Lions (7-8) disappeared in a 23-20 overtime loss to the New York Giants and the Green Bay Packers (7-7-1) fell 38-31 to the Steelers on the Frozen Tundra at snowy Lambeau Field.
The Seahawks entered Sunday with the NFL's best record and unbeaten at home for two seasons but fell to 12-3 after being upset by the surprising Arizona Cardinals (10-5), who kept their own playoff dreams alive with a gritty 17-10 victory.
Cardinals quarterback Carson Palmer threw four interceptions but the Arizona defense could not be breached as Seattle failed to secure the NFC West division crown and home field advantage throughout the playoffs after suffering their first home defeat since December 24, 2011.
Three more teams confirmed their invitations to the post-season party on a pulsating penultimate Sunday that dripped with of high drama and nail-biting action.
Nowhere were tensions running higher than in Charlotte, North Carolina where Carolina quarterback Cam Newton engineered a last gasp touchdown drive to cap a thrilling 17-13 win over the New Orleans Saints (10-5) and give the Panthers (11-4) their first trip to the post-season since 2008.
After Drew Brees had marched New Orleans 97 yards, hitting Jimmy Graham for a go ahead touchdown, Newton went right to work, preventing the Saints from clinching the NFC South division crown and a first round playoff bye.
With 55 seconds left on the clock and no timeouts, Newton took the Panthers 65 yards on five plays hitting Domenik Hixon with a 14-yard touchdown strike to stun the Saints and send the sellout Charlotte crowd into wild celebration.
"Man it was so close," said Newton. "We have to win games like this, it wasn't pretty but this is the definition of a playoff team, a playoff game, real close.
"We depended on the defense at times but when we needed to score we did."
DALTON LEADS BENGALS
In Cincinnati, Andy Dalton tossed four touchdowns as the Bengals (10-5) pounded the Minnesota Vikings 42-14 to clinch a playoff berth.
That result coupled with Miami Dolphins loss to the Buffalo Bills was enough to earn the Bengals a third straight playoff appearance.
Later on Sunday, the Bengals had more to celebrate when the Patriots crushed the Ravens 41-7 earning Cincinnati the AFC North crown.
Even before New England (11-4) had kicked off against Baltimore they had clinched a fifth straight AFC East crown and playoff spot when the Dolphins (8-7) were upset 19-0 by the Bills in icy Buffalo.
In Houston, Peyton Manning enjoyed a record smashing day throwing four touchdown passes as the Broncos (12-3) tamed the Texans 37-13 nailing down a third consecutive AFC West division title and a first round bye after the Chiefs (11-4) were surprised 23-7 by the Colts (10-5).
Manning's four touchdown strikes gave him 51 for the season eclipsing the record of 50 set by the Patriots' Tom Brady in 2007.
The Dallas Cowboys (8-7) kept their post-season hopes alive when Tony Romo found DeMarco Murray with a 10-yard touchdown strike with just 68 seconds left on the clock to eke out a 24-23 win over the Washington Redskins.
The victory sets up a winner-take-all showdown next Sunday against the Philadelphia Eagles (8-6) in the regular season finale that will decide the NFC East champion.
The San Diego Chargers remained in the AFC playoff picture with a 26-13 win over the Oakland Raiders.
(Reporting by Steve Keating in Toronto, Editing by Gene Cherry)