Marathon negotiations between National Basketball Association (NBA) owners and players failed to deliver a new labor agreement Thursday but both sides left negotiations vowing to continue talks to end the lockout.

There are no guarantees that we're going to get it done, NBA commissioner David Stern told reporters at the end of a negotiating session at a Manhattan hotel. But we're going to give it one heck of a shot tomorrow.

After meeting for 15 hours Wednesday, owners and players returned to the negotiating table Thursday and met for nearly eight hours but were unable to end the four-month old dispute although there was increasing optimism that an agreement was within reach.

More talks are planned for Friday.

I think we're within striking distance of getting a deal, said players union boss Billy Hunter.

Negotiations on a new collective bargaining agreement picked up steam after reports earlier this week suggested the league was ready to axe two more weeks from the schedule after already cancelling the opening two weeks of the regular season.

If an agreement can be reached by the weekend there are hopes a full 82-game season, which was originally scheduled to begin on November 1, might still be played.

Details from the latest round of talks were not released but it is believed the main stumbling blocks remain how the two sides will divide basketball-related income and the structure of the salary cap system.

NBA owners contend the league lost $300 million last season with 22 of 30 teams in the red and initially demanded players cut their share of revenue -- which was 57 percent under the previous agreement -- to 47 percent along with a firm salary cap and shorter contracts.

The players have lowered their proposal to 52.5 percent.