When the NFL launched its regular season three years ago with a nationally televised game on Thursday night, some questioned whether the league risked over-extending itself by venturing beyond its successful, decades-old formula of opening with a full slate of Sunday games.

Tonight, when the New England Patriots begin their pursuit of a fourth Super Bowl title in five years against the Oakland Raiders in Foxboro, Mass., those questions have gone away. Indeed, the league now hopes to make its season-opening Thursday night game into the second-biggest evening of the NFL calendar after the Super Bowl.

Such lofty goals are commonplace in the NFL, which over the past decade has grown from its No. 1 perch on the U.S. sports landscape to the point that it now dwarfs Major League Baseball and the NBA, the country's two other major professional team sports. It is the richest and most highly rated professional league in the United States and has become a major force in popular culture, with its imprint stamped on video games, music and fashion.

"I think the game in some ways sums up the American experience," said Neal Pilson, the former president of CBS Sports who is now a sports TV consultant. "I think a lot of people see their daily lives and the history of the country in the NFL because the game is also linked to the personality and the attitude of the country. There's a high degree of teamwork, an emphasis on toughness."

Even more vital to its success has been the keen business sense and marketing savvy of the league's leaders. At a time when viewership of most professional leagues is in steep decline, the NFL this offseason completed a new set of broadcast contracts with Fox, CBS, NBC, ESPN and DirecTV that will pay the league nearly $4 billion per year in rights fees -- up from the approximately $2.8 billion that it will earn this season from its expiring TV deals.

"It is the perfect sport for television," said Artie Kempner, the lead game director for Fox. "There are natural timeouts and stoppages in play so you can show replays and get the commercials in without missing any action. The fact the games are a week apart allows for a tremendous buildup."

Things were far from perfect for the NFL in recent months. Commissioner Paul Tagliabue and players' union chief Gene Upshaw were summoned to Capitol Hill to be questioned by lawmakers as part of the congressional scrutiny of steroid use in sports. Their appearance followed reports that players for the Carolina Panthers filled steroid prescriptions by a Columbia, S.C., physician within weeks of playing in the Super Bowl in February 2004.

San Francisco 49ers offensive lineman Thomas Herrion collapsed in the locker room and died after an Aug. 20 preseason game in Denver. Although the coroner this week said Herrion likely died from heart disease, the death of the 23-year-old lineman, who was listed at 315 pounds, called attention to a growing obesity problem in the league.

The New Orleans Saints were displaced from their home city after it was ravaged by Hurricane Katrina and flooding.

Among the challenges facing the NFL in the near future are getting owners to agree to a plan for increased revenue-sharing among teams as part of a new labor deal and getting a franchise in Los Angeles, the nation's second-largest television market.

A bigger long-term issue is finding a successor to Tagliabue, who has three years remaining on his contract. Several owners said that Tagliabue has told them he almost certainly will retire when it runs out in 2007 and they indicated there have been informal discussions among some owners about who will replace him and become only the fifth commissioner in league history.

"Paul has made it clear that he's not for long," Dallas Cowboys owner Jerry Jones said in a recent interview. "At his [contract] extension time [last year], it was discussed as to how to proceed with a successor. I would say it's on an informal basis. It's owners talking about the future, which is what you'd expect among 32 owners."

Tagliabue, 64, earns about $8 million a season, a salary that befits his status as one of the most powerful men in American sports. When he was named commissioner in 1989, Tagliabue was not the first choice of a six-man selection committee, which recommended Jim Finks, a longtime team executive and former player, as the successor to Pete Rozelle. A New Jersey native who lived in Washington at the time, Tagliabue had been the league's lead attorney and was virtually unknown to the public.

Before he was elected by owners on the 12th ballot, he told them he was committed to finding new sources of revenue and would become far more involved than his predecessor in the collective bargaining process with the NFL Players Association.

He has been hugely successful on both fronts. When Tagliabue took over the NFL, league-wide revenues were at $970 million, with each team getting $16.2 million a year from television. This year, revenues will total about $5.7 billion, with each team getting $87.5 million from TV -- a windfall that spurs competition and gives fans in each of the league's 32 cities reason to hope that their team has a fair shot at making it to the Super Bowl.

Over his tenure, there has never been a labor-related work stoppage of the kind that have bedeviled MLB and the NHL, though contentious negotiations on a possible fifth extension of the collective bargaining agreement since 1993 are now in their final stage. In addition, Tagliabue has been able, at least so far, to prevent steroid use in the NFL from becoming a controversy on the scale of that roiling baseball. Tagliabue declined to be interviewed for this story.

When Tagliabue does step down -- and some owners hope to persuade him to stay on after his current contract runs out -- the league could be in store for a major organizational change. Houston Texans owner Robert McNair said he favored having two people the top of the NFL: one in charge of football, the other strictly involved with the business of the game.

"The job of commissioner has grown so much," McNair said. "At this point in time, I really believe that it's two jobs. . . . As we go forward, I think it's expecting too much that any one person could do a good job in both positions."

Lamar Hunt, longtime owner of the Kansas City Chiefs, said he would oppose splitting the job. "I don't think the system is broken," he said. "I'd keep it the way it is. One of Paul's great strengths has been his ability to put a lot of very talented people in place in the league office. He's done a great job with the football end of it and the business end of it, and I think we'd make a mistake if we changed the structure of the commissioner's office."

Meantime, football's leaders have continued to tinker with their on-the-field product. They tweaked the rules before last season to handcuff defenders and make top quarterbacks and receivers virtually indefensible, and got the sort of record-setting passing performances last season they'd been seeking. The trend should continue this season, since the rules-makers offered defenses no reprieve.

"The NFL always seems open to innovation," said Steve Sabol, head of NFL Films. "Take the opener on Thursday. Now they take one game, make it special and have a celebration around it leading into a weekend of 'Kickoff Sunday.' That's great marketing."

Broadcaster John Madden said he is among those concerned about the possible over-saturation of the sport, with games now played weekly on Sunday night and occasionally on Thursday night and Saturday in addition to the usual fare on Sunday afternoon and Monday night.

But the former Raiders coach, who was recently nominated for induction into the Pro Football Hall of Fame, added: "The league can't cannibalize itself. The way it's set up now, you play on Monday night, and then you don't get another game until Sunday afternoon for most of the season. In other sports, if you miss a game today, you can see another one tonight or another one tomorrow. In football, you only play once a week and you only play 16 weeks, so the interest stays up.

"No matter what they do," Madden said, "they can't really screw it up."

Patriots quarterback Tom Brady, top left, and Coach Bill Belichick, lower left, are pumped up about winning another Super Bowl trophy. Their first opponent is the Oakland Raiders, who strengthened their offense by adding running back LaMont Jordan, middle, and wide receiver Randy Moss.Patriots owner Robert Kraft, left, chats with former president George H.W. Bush and first lady Barbara Bush before last season's Super Bowl in Jacksonville.