NFL players will begin heading to training camps this weekend, ending their vacations to pull on pads in the summer heat and sweat through the rudimentary drills of the new football season. For most, the goal will be to make it to Super Bowl XL in Detroit; for the New England Patriots, the motivation is more historic.

The Patriots are the league's model franchise, with three titles in four years and the opportunity to become the first team to win three straight Super Bowls. In an era of supposed parity, with the game designed to allow teams to quickly rise from the dregs to the playoffs, New England is a dynasty. The loss of the Patriots' two top coordinators -- Romeo Crennel and Charlie Weis departed for head coaching jobs -- and Pro Bowl linebacker Tedy Bruschi, who is out for the season recovering from a stroke, could make the Patriots vulnerable. But as training camps open -- with the Chicago Bears the first to report today -- 31 teams are still chasing New England.

"What we all want to replicate is to win like that," Baltimore Ravens General Manager Ozzie Newsome said. "I think the reason we're all still chasing the Patriots is because of the head coach [Bill Belichick] and the quarterback [Tom Brady]. Continuity is very important, because you have been in the foxhole with those guys and you know what to expect, but sometimes change can be good also. Everybody loves continuity, but you can't be afraid of change."

The Washington Redskins are one of the final teams to reconvene, as they do not report to training camp until July 31, and will hold their opening practice the following day. They scrimmage the Baltimore Ravens the following weekend and hold their annual fan day that weekend as well.

Training camps are becoming shorter because of expanded offseason workout programs, and much of this spring's NFL drama will be the top story lines of the summer. Agent Drew Rosenhaus led a stable of premier players on offseason workout boycotts. Most notable is Philadelphia Eagles wide receiver Terrell Owens, who had threatened to sit out indefinitely because he's unhappy with his contract. He said yesterday he would report to camp, but hinted that he would agree to a trade. Faced with having to repay $8.6 million to the Miami Dolphins for breaching his contract, running back Ricky Williams spent months negotiating a return to the league after his abrupt retirement last year and he is expected to return this weekend -- to a team now coached by Nick Saban. Williams will sit out four games because of substance abuse violations.

The return of Green Bay quarterback Brett Favre after he considered retirement adds luster to a position that hardly lacks star power. Favre, 35, remains a dangerous force and has coped with death and serious illness within his family, including his wife's breast cancer battle.

"I did my best to let time kind of take its course," Favre said during a recent interview on ESPNews, "and not make any quick decisions [about retirement]. Once my wife got a clean bill of health, she was adamant about me coming back and playing."

Several candidates stand ready to take Favre's place in the spotlight. Atlanta's Michael Vick has the physical skills, but must still round into a true passer. Donovan McNabb has led the Eagles to the cusp of glory; Indianapolis's Peyton Manning set the all-time touchdown mark last season but playoff success has been elusive for the Colts. Each of those players enters camp believing a Super Bowl is within grasp, and considering that 22 of the NFL's 32 teams have reached the playoffs in the three seasons since divisional realignment, they are hardly alone.

"I think the story of the NFL is the unpredictability," said Houston Texans General Manager Charley Casserly. "Outside of Philly and New England, we've seen multiple changes of division winners. That's the story and the fascinating part of our league. There is no predictability to it. Everyone comes into camp hoping this is the year they break through. That's the great thing about our league. You know there's going to be some great story out there, you just don't know where it's going to be."

There is uncertainty about the future of NFL labor relations as well. Negotiations between the league and the NFL Players Association are ongoing, with both sides optimistic about a resolution that would extend the collective bargaining agreement. The deal expires after the 2006 season, which would leave the 2007 season without a salary cap. In that case, teams could spend what they please, likely altering what has been an extended period of competitive balance because of the cap, which limits teams' payrolls. Already, this possibility is affecting contract talks with top draft picks, several NFL executives said.

"The lack of a new agreement right now is going to impact the top 10 [picks]," Newsome said, "and it could end up impacting the whole first round. I know that from our standpoint in Baltimore, we don't feel like having that uncapped year would be a successful thing for the National Football League. We just don't feel that way. And being an ex-player, if I got to a place where I could get to an uncapped year in free agency, I think I'd love it."

Some big-spending owners, like Washington's Dan Snyder, likely would not mind such a scenario, either, and the chasm between large- and small-market clubs threatens to intensify. Still, early signs indicate that there is enough common ground to bring about a deal.

"We have a great system that has benefited everyone and we are working hard to bridge the gap with the players' association," said Harold Henderson, the NFL's executive vice president of labor relations. "We have significant differences and we are trying to develop new concepts to resolve some difficult issues. But our system has been so productive on so many levels that the only sensible outcome is to extend the CBA a fifth time."

Green Bay's Brett Favre is back; he had considered retiring after his wife was diagnosed with breast cancer, but she has gotten a clean bill of health.