The Denver Broncos, San Francisco 49ers and New Orleans Saints confirmed their championship ambitions with impressive wins while the New England Patriots and Super Bowl champion Baltimore Ravens had worrying flaws exposed.
Over the course of a 16-game season more challengers will surface while others fade, but in January, barring injuries to their star quarterbacks, the Broncos, 49ers and Saints should all be competing for Super Bowl berths.
As is typical, the season's opening week of games did not produce the highest quality performances from teams, coaches or officials.
But some players were quick out of the blocks, led by Broncos quarterback Peyton Manning, who opened the new campaign by tossing a record-equalling seven touchdown passes in a 49-27 demolition of the Ravens.
Denver, preseason favorites to win the Super Bowl, should only get better, particularly on defense, when All-Pro defensive back Champ Bailey returns from injury and Von Miller serves his six-game doping suspension.
A Ravens title defense suddenly seems a longshot after Manning shredded a Baltimore defense that was without retired inspirational leader Ray Lewis and safety Ed Reed for 49 points -- the most ever surrendered by the franchise in a single game.
San Francisco quarterback Colin Kaepernick could not match Manning's magic but looks ready to build on last year's breakout season after tossing for a career-high 412 yards and three touchdowns in a 34-28 win over the Green Bay Packers.
The 49ers used the opener to unveil their newest offensive weapon, wide receiver Anquan Boldin, who hauled in 13 catches for 208 yards and a touchdown after coming over from the Ravens in the offseason.
"(Kaepernick) did exactly what he's capable of doing," Boldin said. "He did exactly what he needed to do. He's a quarterback first. Being able to run is just a bonus."
While the Niners and Packers were on top of their games, officials made a major fumble when they mistakenly ordered San Francisco to replay a down after a sideline scuffle featuring Green Bay's Clay Matthews and 49ers' Kaepernick and Joe Staley.
In Buffalo, the Patriots earned their 10th straight opening-day win but needed a 35-yard field goal from Stephen Gostkowski with five seconds left to eke out a nervy 23-21 win over the feisty Bills.
After sitting out all last season for his role in the pay-for-pain 'Bountygate' scandal, Saints head coach Sean Payton returned on Sunday and it was like old times as New Orleans disposed of the division rival Atlanta Falcons 23-17.
If the Broncos, Saints and 49ers delivered the good in Week One, the New York Giants provided the bad and the ugly after committing six turnovers in a fright-filled 36-31 loss to the host Dallas Cowboys in primetime Sunday Night horror show.
"You're never going to win a game turning the ball over five times and muffing a punt," said Giants coach Tom Coughlin. "Six times we gave the ball away to them. Six times. That's my fault.
"I'm totally, totally disappointed and embarrassed by that kind of football. That's sloppy, sloppy football."
Fans of the Jacksonville Jaguars and Cleveland Browns, both playing at home, were left disappointed and looking at the prospect of settling in for a long, dreary season following a 28-2 loss to the Kansas City Chiefs and 23-10 loss to the Miami Dolphins, respectively.
Opening weekend also delivered a few surprises as the New York Jets and rookie quarterback Geno Smith edged the favored Tampa Bay Buccaneers 18-17 and the Tennessee Titans downed the Pittsburgh Steelers 16-9.