After a 5-0 start, the Chiefs were supposed to run away with the AFC West, but Kansas City now find themselves in a three-way tie atop the division.
Sunday's 38-31 loss to the New York Jets was Kansas City's fourth straight as they were left at 6-6.
The Los Angeles Chargers rolled to a 19-10 win over the Cleveland Browns while the Oakland Raiders got past the New York Giants in a 24-17 victory as both teams pulled even with the Chiefs.
Despite an 0-4 start, the Chargers have become the favourites to win the West. The Bolts are the division's hottest team and face both the Chiefs and Raiders over the final month. The Chargers host the Redskins next week and travel to face the Jets on Christmas Eve.
The Raiders and Chiefs get together next week at Arrowhead Stadium, but the Raiders then face the Cowboys (6-6) and Eagles (10-2) before closing the season with a road game against the Chargers. The Chiefs probably have the most favourable schedule with home games against the Raiders and Chargers over the next two weeks before taking on the Dolphins (5-7) and Broncos (3-9) to close the year.
While the Chiefs are slowly falling out of the AFC play-off race, the Packers are suddenly back in the NFC hunt after Sunday's overtime win over the Buccaneers.
The Packers (6-6) play the winless Browns next week and could get starting quarterback Aaron Rodgers back from a broken collarbone for the final three games. His potential return is the December 17 game at Carolina as the Packers expect to make one last postseason push.
The Packers own tiebreakers over the Seahawks (8-4), who beat the Eagles on Sunday, and Cowboys. The regular-season finale against the Lions (6-6), who won at Lambeau Field earlier this season against a Rodgers-less Packers team, could be for a play-off spot.
CAMPBELL CONTINUES GOOD FORM
Jaguars defensive end Calais Campbell is having a great first season in Jacksonville. The 10-year veteran set a single-season franchise record after getting a sack Sunday against the Colts to give him 12.5 for the season. He can add to that record with four games remaining.
Patriots quarterback Tom Brady threw for 258 yards against the Bills to join Peyton Manning, Brett Favre and Drew Brees as the only quarterbacks in NFL history with at least 65,000 career passing yards.
The Colts were blown out by the Jaguars, but Frank Gore rushed for 61 yards to move past Hall of Famers Jerome Bettis and LaDainian Tomlinson for fifth place on the NFL's all-time rushing list.
Cardinals receiver Larry Fitzgerald caught 10 passes for 98 yards in a 32-16 loss to the Rams and passed former Rams receiver Isaac Bruce for fourth place all-time in receiving yards. He also joined Jerry Rice and Tony Gonzalez as the only players in NFL history with at least 1,200 career receptions.
JAGUARS' FAKE PUNT, COHEN CRUISES
A 29-yard pass from Jaguars punter Brad Nortman to a wide-open James O'Shaughnessy resulted in a 29-yard gain, and the fake punt set up Jacksonville's first touchdown in Sunday's 30-10 win over the Colts.
Bears rookie Tarik Cohen retreated before reversing direction and then weaving his way through the 49ers coverage team for a 61-yard punt return for a touchdown.
The Packers avoided a fourth straight home loss thanks to Aaron Jones' game-winning 20-yard touchdown run in overtime to beat the Buccaneers.
Derrick Henry's 75-yard touchdown run put the exclamation point on Tennessee's 24-13 win over the Texans.
Mark Ingram's 72-yard run helped set up his own three-yard touchdown in the second quarter of the Saints' 31-21 win over the Panthers.
'DIRTY' GRONKOWSKI SLAMMED
Bills safety Micah Hyde on Gronkowski's late hit on Tre'Davious White: "Just a dirty play. That's something that the NFL talks about not wanting. The refs, if they didn't see it live, then they had a good chance to see it on the replay. It was just a dirty play."
49ers quarterback Jimmy Garoppolo on going back home to beat the Bears: "I had a ton of people here today and it was special having them in the stands. Lot of red tens out there so it was cool."
Minnesota Vikings 14-9 Atlanta Falcons
Baltimore Ravens 44-20 Detroit Lions
New England Patriots 23-3 Buffalo Bills
San Francisco 49ers 15-14 Chicago Bears
Green Bay Packers 26-20 Tampa Bay Buccaneers
Jacksonville Jaguars 30-10 Indianapolis Colts
Miami Dolphins 35-9 Denver Broncos
New York Jets 38-31 Kansas City Chiefs
Tennessee Titans 24-13 Houston Texans
Los Angeles Chargers 19-10 Cleveland Browns
Los Angeles Rams 32-16 Arizona Cardinals
New Orleans Saints 31-21 Carolina Panthers
Oakland Raiders 24-17 New York Giants
Seattle Seahawks 24-10 Philadelphia Eagles