Nelson dismissed the NFL's argument that she didn't have jurisdiction and that it's facing irreparable harm because of her decision to end the 45-day lockout at the request of the players.

"The world of 'chaos' the NFL claims it has been thrust into — essentially the 'free-market' system this nation otherwise willfully operates under — is not compelled by this court's order," Nelson wrote.

James Quinn, a lawyer for the players, said free agency — the biggest immediate question for owners and players alike — should start immediately.

NFL spokesman Greg Aiello said the league was "evaluating the district court's decision" and would advise teams Thursday morning on how to proceed.

The NFL Players Association, now a trade group and not a union, accused the league of stalling.

"On the eve of one of the greatest fan events in sports, the players moved another step closer to bringing the fans football," spokesman George Atallah said in an email to The Associated Press. "Owners seem determined to prevent that from happening. The NFL owners are not litigating to protect the game. They're litigating to protect a lockout."

The NFL said the appeals court is "likely to reverse" Nelson's decision and claimed her injunction that lifted the lockout is "skewing" the collective bargaining process. Owners and players must eventually reach a new CBA to ensure a 2011 season.

The NFL argued that a stay is necessary to avoid irreparable harm to league operations, even quoting an unidentified NFLPA executive: "If the lockout is lifted and a stay isn't granted, it could be utter chaos."

Without a stay, the NFL said, it would be impossible to "unscramble the egg in terms of player transactions (trades, signings, cuts) that would occur in the interim" before a ruling from the appeals court.

The league even proposed a specific timeline for the process: a written opening argument due May 10, the same due for the players May 24, the NFL's reply due May 31 and a hearing after that "as soon as possible."

That means the legal fight would stretch well into June, a month before training camps and only weeks before the first scheduled preseason game on Aug. 8.

In the 23-page motion, the league mostly reiterated three main arguments it unsuccessfully made to Nelson: that she had no jurisdiction while a bad-faith negotiation charge against the players is pending with the National Labor Relations Board; that federal law prevents the court from overseeing any cases at all that stem from labor disputes; and that it shouldn't be subject to some of the antitrust claims leveled by the players with the collective bargaining deal barely expired.

The league said Nelson "brushed aside all three legal obstacles with the simple rationale that the NFLPA's unilateral disclaimer changes everything and renders the labor laws irrelevant." The NFL, citing comments by players Mike Vrabel and Derrick Mason, argued again that the union's breakup was only temporary and tactical and not permanent.

Nelson's ruling was not a surprise, given her questioning of NFL attorney David Boies during an April 6 hearing and her 89-page order lifting the lockout. She wrote another 20 pages in her denial, declaring the public's interest in the resumption of league operations.

League rules have effectively been shelved since the collective bargaining agreement ended on March 11 and the NFL's first work stoppage since 1987 began.

Nelson said that needn't be the case.

She suggested that the NFL "make a decision about how to proceed and accept the consequences" of that choice. In saying the NFL could go about its business, Nelson noted that the league had already gone forward with the draft and announced the 2011 schedule.

Nelson also pointed to the contract tenders teams issued to restricted free agents in March before the lockout, "treating them as if the league intended to operate with the 2010 rules in place."

What the NFL will do Thursday was anyone's guess, though Packers president and CEO Mark Murphy suggested earlier the 2010 rules might be used.

"What we would probably do if Judge Nelson and the 8th Circuit deny our request for a stay would be play under the same rules that we had last year," Murphy said Tuesday. "It's 2010 rules, those were agreed to by the players in the collective bargaining agreement, I think that's probably the rules that make the most sense."

Bears safety Chris Harris put it this way on his Twitter feed: "Owners have to open doors. Its impossible to start the NEW LEAGUE YR without Free Agency."

The antitrust claims were first brought up in a still-pending lawsuit led by Tom Brady, Drew Brees and others. Nelson said the claims have not been aired and are therefore not up for discussion yet.

"There is no injunction in place preventing the NFL from exercising, under its hoped-for protection of the labor laws, any of its rights to negotiate terms and conditions of employment, such as free agency," she wrote. "The Eighth Circuit will not even be addressing, much less ruling on, player restraints, free agency, etc., for the simple reason that this court did not rule on those issues."

The league's plea to Nelson for the stay also was based on a purported fear that an immediate lifting of the lockout would result in a free agency free-for-all that could create a mess that would be difficult to undo should a new collective bargaining agreement lead to different rules.

Nelson called that an "incorrect premise." She insisted that her order was simply an end to the lockout.

The two sides had 16 days of talks with a mediator earlier this year, and four more with a federal magistrate that were ordered up by Nelson. Little progress has been seen, and the two sides are scheduled to meet again May 16.

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AP Football Writers Howard Fendrich and Barry Wilner contributed to this report.