By Steve Keating

DALLAS (Reuters) - The NFL's chief negotiator warned Wednesday that the clock is ticking down on reaching a new collective bargaining agreement, delivering a sobering message as the Super Bowl party gets set to kick into high gear.

Jeff Pash, the league's lead attorney and chief labor negotiator, challenged the NFL Players Association to get serious about negotiations or both sides risk devastating consequences.

"The point we have been trying to emphasize is that both sides have very substantial incentives to try and get an agreement done by March 4," Pash told reporters. "We know we will have adverse revenue affects and while revenue losses will be significant they will grow and they will be accumulative.

"We need to get busy and we need to get busy now."

Key issues include how league revenues will be split by the sides, the possible move to an 18-game regular season, a rookie wage scale and pensions for former players.

Earlier this week the two sides agreed to a series of labor talks with the first scheduled for Saturday, one day before the Pittsburgh Steelers and Green Bay Packers meet in Super Bowl XLV.

At risk is the NFL's $9 billion of annual revenue, which research firm IBISWorld estimated could grow to $9.8 billion next year if a work stoppage can be avoided.

The league is coming off perhaps its strongest year ever.

Regular season games reached almost 208 million unique U.S. viewers, the highest total ever, and were also the most-watched program each week during the season.

But NFL owners maintain they are operating under an unsustainable business model and seeking sizeable concessions from the players.

"We are not looking for an agreement that will swing the pendulum as far in our direction as it currently has been swung in direction of the players," said Pash. "We want something that is fair and works for both sides."

While the NFL's 2011-12 season is not scheduled to kickoff until September, the pressure to get a deal done is mounting.

Pash warned that close to 500 players will become free agents in March and could miss out on lucrative bonuses and contracts if a new labor deal is not reached.

The league would also feel the pain since revenue losses are projected at close to $1 billion if they are without an agreement in September.

"It is a date of very considerable significance," warned Pash. "If you make a deal September 1 there is overwhelming pressure to get the games going but you can't just start five days later.

"How would you put your rosters together?

"It becomes really quite challenging if you let it get to that point."

Pash said the critical issue for owners is the overall economics and structure of the salary cap going forward.

"Over the last 10 years player compensation has doubled," said Pash. "If we have an economic system that works we could do that again.

"Maybe we would have a franchise in London. We could have bigger rosters and more jobs ... there is a lot out there, things small minded lawyers can't even dream of but we need a system that fuels it."

(Editing by Frank Pingue)