PHILADELPHIA -- A Philadelphia judge on Monday ordered lawyers for the National Football League and thousands of its former players to try to settle claims that the league hid or ignored evidence that concussions lead to brain damage.

After a telephone conference with the case lawyers, U.S. District Judge Anita B. Brody said she appointed a retired federal judge, Layn R. Phillips, to mediate the talks. She asked Phillips to deliver a report to her by Sept. 3.

The order suspends Brody's plan to rule later this month on the league's request that she dismiss the case entirely. The judge said she won't consider that motion until she gets Phillips' report.

Where the dispute lands is the first major decision in what could be a billion-dollar case with far reaching implications - not just for the NFL, but for football and other contact sports.

The league denies any wrongdoing and maintains that concussion-related claims are safety issues governed by its contract with the players union, and thus should be resolved in confidential labor arbitration.

The players want their cases heard in open court, arguing that league officials committed a fraud not contemplated or covered by any collective bargaining agreement.

More than 4,000 former players or their estates have filed lawsuits nationwide, which were consolidated last year under Brody in Philadelphia.

Spokesmen for the players and the NFL on Monday said both sides would honor the judge's order and meet with Phillips.

The move into mediation is not uncommon.

It could keep details of the dispute out of public view - Brody specifically ordered the talks to remain confidential. But it doesn't guarantee a resolution, as would an arbitration, in which both sides present their case and leave it to an independent third party to issue a ruling that can't be appealed.

"A mediation is an effort to bring the parties to an agreement," said John Bissell, the former Chief U.S. District Judge for New Jersey who has worked as a mediator for eight years. "If such an agreement is not achieved, then you have no result. The mediator cannot impose an outcome."

A mediator could bring the two sides together on some issues, but not all. The particulars of when and how the talks proceed will be up to Phillips and the parties.

Bissell said sometimes it makes sense for a mediator to keep the two sides separate, at least at the outset, to absorb their views and appreciate the scope of the dispute.

He said he didn't know Phillips personally but knew his reputation as a mediator. "I doubt there will be any stone unturned here," he said.

Phillips was a federal prosecutor and judge in his home state of Oklahoma before resigning in 1991 to enter private practice in Newport Beach, Calif.

A spokeswoman at his office said the former judge had no comment Monday except that he was "pleased" to be appointed and looked forward to working toward a resolution.

It's unclear how Phillips was chosen or if others were considered. Brody's order said she had asked lawyers on both sides to identify mediators "experienced in resolving complex matters."

According to a biography posted on his firm's website, Phillips was a standout college athlete - in tennis, not football.

In 1998, he launched a successful mediation center that has since counted Fortune 500 companies as clients. His biography says Phillips "is considered pre-eminent in the resolution of multi-party matters, some involving as many as 150 parties."

He mediated the talks that led last year to a $2.4 billion payment by Bank of America to settle shareholder claims over its 2008 buyout of Merrill Lynch. He also helped bring about a $13.5 million class action settlement with Wal-Mart Stores Inc. over claims related to its retirement plan fees.

But not every case is a success.

Phillips was twice recruited to mediate settlement talks over the collapse of the bankruptcy liquidation of onetime tech giant Nortel Networks, but the talks, in 2010 and 2011, failed. Still, Phillips was paid $1,000 an hour plus expenses for his work, according to documents filed in that case.

Brody's order doesn't specify Phillips' fee or set limits or other parameters for his work on the concussion matter.