By Simon Evans
MIAMI (Reuters) - The National Football League (NFL) season gets underway with a bang on Thursday as the past two Super Bowl champions, the Green Bay Packers and the New Orleans Saints, go head-to-head at a packed Lambeau Field.
While defending a title in the NFL has proved to be a notoriously tough task, it has happened only eight times since the first Super Bowl in 1967, there is a real sense that the Packers have a chance of a second straight Super Bowl triumph.
Mike McCarthy saw his team get their hands on the Vince Lombardi Trophy last season despite having 17 players on the injured reserve and he now has most of those starters available again -- including tight-end Jermichael Finley.
Finley's return gives quarterback Aaron Rodgers, who already has an abundance of targets in an impressive receiver corps, another option which should make the Packers even more of a threat offensively.
The aggressive defense that was so crucial to the Super Bowl win over the Pittsburgh Steelers is, if anything, even stronger this season and Saints quarterback Drew Brees believes he will be up against one of the best defenses around.
"Their defense as a whole is aggressive, they get after the quarterback, they make a lot of turnovers, make a lot of plays and play with a lot of confidence," said Brees.
The Saints have overhauled their running backs after releasing Reggie Bush and have also been boosted by head coach Sean Payton's agreement to a contract extension that will keep him with the franchise until 2015.
Such stability on and off the field -- the Saints have had the same head coach, general manager and quarterback for the past five years -- is the envy of many in a league where there has been, as usual, a great deal of roster movement. Eight teams will start this season with new head coaches.
The Seattle Seahawks, who begin their campaign at San Francisco on Sunday, have only 10 of 53 players left from those inherited by head coach Pete Carroll at the end of the 2009 season.
Some teams have left big decisions late -- the Jacksonville Jaguars released their long-term starting quarterback David Garrard on Monday, just five days before their opener at home to the Tennessee Titans.
The Indianapolis Colts will also launch the season with a new quarterback, though there was no question of choice involved in having to leave out Peyton Manning, who is still recovering from a neck injury.
Four-times MVP Manning will be replaced in Sunday's game against the Houston Texans by veteran back-up Kerry Collins, who has come out of retirement for the unenviable task of filling in for one of the best quarterbacks ever.
Receiver Chad Ochocinco and lineman Albert Haynesworth were two surprise additions to the New England Patriots' roster and will make their debuts in the Monday night game at the Miami Dolphins.
The Dolphins looked likely to be one of the teams undergoing major rework this offseason but first coach Tony Sparano and then quarterback Chad Henne were given one more chance to prove they can get the Florida team back into the playoffs.
Sunday's most intriguing match-up sees the Dallas Cowboys, with Tony Romo fit again to lead from quarterback, travel to the New York Jets.
There is some strong sibling rivalry involved in that battle with Rob Ryan, the Cowboys' defensive coordinator, coming up against his twin brother Rex, head coach of the Jets.
(Editing by Mark Lamport-Stokes)