New York - The NHL and the players' association returned to the bargaining table Thursday, the third straight day the sides have met in an effort to end the lockout.

The work stoppage reached its 54th day, and this week is considered critical for the hockey season to be saved. The lockout is threatening to force the second cancellation of an NHL season in seven years.

Even if an agreement is reached soon, it isn't clear if any of this season's games that have been called off through Nov. 30 can be rescheduled. The NHL has already said a full 82-game season won't be played.

Owners and players had bargained for many hours over two days this week at an undisclosed site in New York. Little information about the talks has been disclosed by either side.

Thursday's discussions marked the fourth time in six days that face-to-face negotiations have taken place after both sides rejected proposals Oct. 18. The lockout, which began Sept. 16 after the collective bargaining agreement expired, has forced the cancellation of 327 regular-season games, including the New Year's Day Winter Classic in Michigan.

During a second consecutive day of marathon negotiations Wednesday, the players' association made an offer on revenue sharing, in which richer teams would help out poorer organizations, and another proposal regarding the "make-whole" provision that would guarantee full payment of all existing multiyear player contracts.

The NHL was expected to respond to both offers during talks Thursday.

Both issues are major hurdles in the way of making a deal. On Wednesday, the sides spent more than five hours dealing with the most contentious areas. Coupled with the more than seven hours they spent negotiating Tuesday, owners and players have been together about 13 hours this week.

"We do not intend to comment on the substance or subject matter," NHL deputy commissioner Bill Daly said in a statement Wednesday night.

NHLPA executive director Donald Fehr said the parties met to "discuss many of the key issues," but didn't elaborate Wednesday.

There is clearly still much to be done to work out the differences to reach a deal that will allow the already delayed and shortened season to begin.

Along with a handful of team owners, eight players attended Wednesday's talks, five fewer than Tuesday. Pittsburgh Penguins captain Sidney Crosby and others left New York to try to avoid the impending snowstorm that hit the area, the union said.

On Thursday, seven players were in attendance, according to the NHLPA.

In October, the players' association responded to an NHL offer with three of its own, but all of those were quickly dismissed by the league. That led to nearly three weeks without face-to-face discussions, although the parties kept in regular contact by phone.

Both sides have made proposals that included a 50-50 split of hockey-related revenues. The NHL has moved toward the players' side in the "make-whole" provision and whose share of the economic pie that money will come from.

Along with the split of hockey-related revenue and other core economic issues, contract lengths, arbitration and free agency also must be agreed upon.

The union accepted a salary cap in the previous labor pact, which wasn't reached until after the entire 2004-05 season was canceled because of a lockout. The union doesn't want to absorb the majority of concessions this time after the NHL had record revenue that exceeded $3 billion last season.