On a day of surprises in the NFL, the San Francisco 49ers suffered a shock 24-13 loss to the Minnesota Vikings, while the New Orleans Saints sank to an overtime defeat to Kansas City.
To add to the surprises, the Cincinnati Bengals spoiled rookie Robert Griffin III's home debut for the Washington Redskins by coming away with a 38-31 win - and the Arizona Cardinals moved to 3-0 with a win over the Philadelphia Eagles.
"We all have fingerprints on it. Now it's a matter of bouncing back and making darn sure it doesn't happen again" - Jim Harbaugh
The biggest upset though was the 49ers, who had already beaten Green Bay and Detroit and were expected to challenge for the Super Bowl.
Vikings quarterback Christian Ponder threw two touchdown passes to tight end Kyle Rudolph, including the game winner in the fourth quarter.
It was an unusually sloppy performance from the 49ers with running back Frank Gore giving up a fumble, quarterback Alex Smith throwing his first interception of the season and David Akers seeing a field goal blocked.
"We all have fingerprints on it. Now it's a matter of bouncing back and making darn sure it doesn't happen again," said 49ers head coach Jim Harbaugh.
"The Vikings did a better job than we did, all the way around. We didn't get it done. There are a lot of reasons. We're not going to start pointing fingers or making excuses."
The Saints, Super Bowl winners three seasons ago and hosts of this season's championship game, now find themselves winless after three games - a position no team has recovered from to win the Super Bowl.
The Chiefs, who had six field goals from Ryan Succop, came back from 18 points down to win 27-24 in overtime.
Their comeback began with Jamaal Charles's stunning 91-yard touchdown run and Succop's sixth successful kick sealed it.
Charles exposed the Saints' weak rush defense again by amassing 233 yards on the ground and he added 55 yards receiving for good measure.
Redskins quarterback Griffin has enjoyed plenty of plaudits this season but it was the much less heralded Andy Dalton who emerged victorious from FedEx Field after throwing for 328 yards and three touchdowns.
Cincinnati wide receiver Mohamed Sanu stole the limelight at the outset when, in the wildcat formation, he threw a 73-yard touchdown pass to A.J. Green.
The Bengals were up 24-10 at the half but a seven-yard Alfred Morris touchdown run and a three-yard pass from Griffin to Santana Moss put the Redskins right back in the game.
Dalton responded with two touchdown passes in the fourth quarter to make Griffin's two-yard touchdown run too late to change the outcome.
The league's other big-name rookie quarterback, Andrew Luck of the Indianapolis Colts, also tasted defeat at the hands of the Jacksonville Jaguars, who notched their first win of the season, 22-17.
Luck threw for 313 yards and two touchdowns with one interception for the Colts but the Jaguars won in spectacular style with quarterback Blaine Gabbert finding Cecil Shorts down the middle and he sprinted into the end zone for a game-winning 80-yard touchdown.
The Eagles had won their first two games but it was impressive Arizona who moved to 3-0, their best start since 1974, thanks to former Philadelphia quarterback Kevin Kolb providing a few points.
Kolb was effectively squeezed out by the arrival of Michael Vick but threw for 22 yards and two touchdowns while Vick fumbled twice - one of which was returned by James Sanders for a 93-yard touchdown.
The Atlanta Falcons, showing their all-round strength again, are also unbeaten after a convincing 27-3 road win at San Diego.
Falcons quarterback Matt Ryan threw for three touchdowns and 275 yards while Tony Gonzalez and Julio Jones put up 91 and 67 receiving yards each and running back Michael Turner piled on 80 yards on the ground.
Peyton Manning suffered his second straight loss with Denver as the Broncos fell to a 31-25 defeat at home to the Houston Texans.
Houston quarterback Matt Schaub threw for four touchdowns and 290 yards while Manning managed 330 yards and two scores.
Sebastian Janikowski's 43-yard field goal on the final play secured a 34-31 win for the Oakland Raiders against the Pittsburgh Steelers.
It was a tough loss for Steelers quarterback Ben Roethlisberg who finished on the losing team despite throwing for four touchdowns and 384 yards.
The New York Jets grabbed an overtime win at the Miami Dolphins thanks to a Nick Folk field goal, although he was given a second chance when his first effort was blocked moments after the referees had blown for a Miami timeout.
And Joe Flacco outdueled Tom Brady in an emotional shootout as the Baltimore Ravens exacted sweet revenge against the New England Patriots with a 31-30 home victory.
The Ravens suffered heartbreak to the Patriots in last season's AFC championship game when a missed field goal attempt doomed their chances, but this time Baltimore converted the knockout blow on a 27-yard field goal by Justin Tucker as time expired.
"We just didn't want to replay last year," Ravens Ray Rice told reporters after rushing for 101 yards and a Touch Down.
"If you go back to the playoff game this game was almost identical. This time we got the win."