NEW YORK (WFAN/AP) — Giants co-owner John Mara joined the NFL group negotiating with the players’ union Tuesday, the first team owner to participate since a federal mediator began overseeing the talks.

Atlanta Falcons president Rich McKay and Washington Redskins general manager Bruce Allen also were among those joining NFL Commissioner Roger Goodell when mediation resumed Tuesday at 1 p.m., 59 hours before the current collective bargaining agreement was due to expire.

“I don’t think you could have a greater sense of urgency,” said Jeff Pash, the league’s lead labor negotiator. “We all know what the calendar is, and we all know what’s at stake for everybody. And that’s why we’re here. We’re going to be here as long as it takes and work as hard as we can work to get something done.”

RELATED: NFL Lockout Looms; Time Running Out On CBA

There was no telling, of course, whether the sides would fare any better Tuesday than they did during more than 40 hours of meetings spread across seven consecutive days of mediation that wrapped up last week. When that round ended Thursday, mediator George Cohen said the league and the NFL Players Association still had “very strong differences” on the “all-important core issues.”

The CBA runs out at midnight as Thursday becomes Friday on the East Coast, and the owners could lock out the players afterward. The union could also decertify — essentially, declare itself out of the business of representing players — and let the players take their chances in court.

Whatever happens between now and Friday could eventually wind up causing the country’s most popular sport to lose regular-season games to a work stoppage for the first time since 1987. Or everything could be resolved by management and labor in an industry with revenues topping $9 billion annually.

The biggest sticking point all along has been how to divide those revenues, including what cut team owners should get up front to help cover certain costs, such as stadium construction. Under the old deal, owners got $1 billion off the top. They entered these negotiations seeking to double that.

Among the other significant topics in negotiations: a rookie wage scale; the owners’ push to expand the regular season from 16 games to 18 while reducing the preseason by two games; and benefits for retired players.

Former player Cornelius Bennett mentioned that last topic as he entered the Federal Mediation and Conciliation Service building Tuesday. He was among the group of about 15 people accompanying NFLPA executive director DeMaurice Smith.

It wasn’t clear how long mediation would continue.

“We want the fans to know that we’re trying. We’re trying. We understand our responsibility, and if we don’t get it done, we know that we’ll have let them down,” the NFL’s Pash said. “And we take that very seriously. So do our owners.”

The 32 teams’ owners were slated to meet Wednesday and Thursday at a hotel in Chantilly, Va., for updates on the status of negotiations.

And then they will need to determine their next step.

In many respects, this boils down to money, of course. And there is plenty of money at risk the longer it takes for the league and NFLPA to work together again.

The league estimates there would be a cut in gross revenues of $350 million if there’s no new CBA by August, before the preseason starts, and a loss of revenues totaling $1 billion if no new contract is in place until September. And if regular-season games are lost in 2011, the NFL figures that revenue losses would amount to about $400 million per week.

If the league locks out the players, everything would stop except the NFL draft on April 28-30, and any interviews or workouts teams hold for college players leading up to the draft. After that, though, teams wouldn’t be able to contact their picks or sign undrafted rookies.

Will the NFL be able to avoid a lockout? Give us your comments below!

(TM and Copyright 2011 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2011 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)

pixy Giants Mara Joins Labor Talks Between NFL, Union

Watch & Listen LIVE