WASHINGTON - Locked in a multibillion-dollar staredown, the NFL and the players' union headed toward the final day of their expiring collective bargaining agreement (CBA) with no word of significant progress and the increasing likelihood of moves that eventually could threaten the 2011 season.

The sides were scheduled to resume federal mediation on Thursday. The current labor deal runs out at midnight Eastern time as Thursday becomes Friday, and among the possibilities are that the union decertifies some time before that deadline; the deadline could be extended; or owners could decide to lock out the players, something the union has expected all along.

Depending on which of those occurs, the country's most popular sport might wind up losing regular-season games to a work stoppage for the first time since 1987. That probably seems unthinkable to football fans who buy tickets and propel TV ratings, helping the NFL become an industry with annual revenues topping $9 billion.