The Carolina Panthers' hopes of completing a perfect season came to an end when they were defeated 20-13 at the Atlanta Falcons on Sunday.
The Panthers thrashed the Falcons 38-0 on their own turf just a couple of weeks ago but could not repeat the feat in Atlanta and slipped to 14-1.
The Falcons improved to 8-7 thanks to a dramatic 70-yard touchdown reception from Julio Jones and 306 passing yards from quarterback Matt Ryan.
Panthers quarterback Cam Newton threw for 142 yards and ran for 46 yards, including an eight-yard scoring run to cap the Panthers' opening drive and put them 7-0 up.
But it was 7-7 at half-time after Falcons running back Devonta Freeman, who finished with 73 yards on the ground, went in from four yards out.
A Graham Gano field goal put the Panthers back in front but Atlanta responded when star receiver Jones, who had 178 yards in total, hauled in a long bomb and then made it into the end zone.
Atlanta padded their lead with a pair of Shayne Graham field goals in the fourth quarter but Carolina got the ball back with 90 seconds left and no timeouts remaining.
Newton completed a 19-yard pass to Corey Brown on first down but then fumbled when he was stripped by Vic Beasley Jr on the following play and Adrian Clayborn recovered for the Falcons to wrap up the win.
Over in the AFC, the Kansas City Chiefs (10-5) beat the Cleveland Browns 17-13 to claim a franchise record-tying ninth consecutive win.
Alex Smith threw a pair of touchdowns for the Chiefs but their offence stalled in the second half and they ended up holding on as the clock ran out on Browns quarterback Johnny Manziel when he was leading a late drive.
The day got even better for the Chiefs because, soon after their game had finished, Baltimore Ravens clinched a 20-17 win over Pittsburgh Steelers, a result which ensured Kansas City will be in the play-offs.
The Steelers defeat means the Cincinnati Bengals, who play the Denver Broncos on Monday night live on Sky Sports, clinch the AFC North title.
Houston quarterback Brandon Weeden scored his first career rushing touchdown and threw for two more as the Texans took a big step toward clinching the AFC South title by routing the hapless Tennessee Titans 34-6.
Houston (8-7), which wraps up the regular season by hosting Jacksonville Jaguars next week, couldn't clinch the title outright however, because the Indianapolis Colts beat the Miami Dolphins 18-12.
Drew Brees passed for 412 yards and three touchdowns as the New Orleans Saints beat the Jacksonville Jaguars 38-27, while the St Louis Rams ended the Seattle Seahawks' five-game win streak with a 23-17 victory.