The Seattle Seahawks needed overtime on Sunday as they found it much more difficult to overcome the Denver Broncos than they did in last season's Super Bowl.
The Seahawks beat the Broncos 43-8 in the showpiece game last season to take the title but this time the clash went to the extra period after finishing 20-20 with Seattle throwing away a 17-3 fourth-quarter lead.
But Marshawn Lynch scored on a six-yard run early in overtime to see the Washington state side home 26-20.
Drew Stanton threw for two touchdowns and 244 yards as the Arizona Cardinals came from behind to beat the San Francisco 49ers 23-14.
The Cards had trailed 14-6 at half-time but Stanton found rookie John Brown in the end-zone twice in the third quarter to turn the game around.
The Dallas Cowboys completed an even more impressive comeback as they overcame the St Louis Rans 34-31.
The Cowboys found themselves 21-0 down in the second quarter but Terrance Williams put them into the lead late in the fourth quarter and Bruce Carter then returned an interception 25 yards to seal the win.
The Kansas City Chiefs claimed their first win of the season with a 34-15 victory over the Miami Dolphins.
Alex Smith threw for three touchdowns and 186 yards despite being sacked five times to inspire his team to victory.
Antonio Brown scored two touchdowns to help lead the Pittsburgh Steelers to a 37-19 win over the Carolina Panthers, while the San Diego Chargers were 22-10 winners over the Buffalo Bills.
The Cincinnati Bengals beat the Tennessee Titans 33-7, the Baltimore Ravens overcame the Cleveland Browns 23-21 and the Detroit Lions triumphed 19-7 over the Green Bay Packers.
The Indianapolis Colts beat the Jacksonville Jaguars 44-17, the New England Patriots were 16-9 victors over the Oakland Raiders, the New Orleans Saints beat the Minnesota Vikings 20-9, the New York Giants saw off the Houston Texans 30-17 and the Philadelphia Eagles were 37-34 winners over the Washington Redskins.
