An arbitrator ruled against the National Basketball Players Association yesterday, deciding that players with guaranteed contracts need not be paid during the current lockout. The decision, on a grievance filed by the union, represented an important victory for the owners in a labor dispute that has already brought cancellation of the first two weeks of the regular season.

The decision yesterday, by John D. Feerick, dean of Fordham Law School, means that N.B.A. owners will not be held accountable for the nearly $800 million in guaranteed contracts held by more than 220 players until the two sides sign a new collective bargaining agreement.

Neither the league nor the players would predict how far the decision would go toward getting the N.B.A. season under way. Via dueling conference calls within hours after the decision, the two sides engaged in more public posturing and sounded as far apart as they were on July 1, the day the lockout began.

''We don't take great pleasure in the current decision,'' said the N.B.A.'s commissioner, David Stern. ''Although it's better than losing, it doesn't take us where we want to be with our players.''

More than 200 N.B.A. players have guaranteed contracts, while another 200 are free agents. Most of the players with guaranteed pacts were due to receive their first paychecks on Nov. 15 -- representing 12 percent of their annual salary. They will not see that money, a harsh economic reality. Yet Billy Hunter, the union's executive director, said the ruling would not lessen the union's resolve. ''We have sufficient money that can take us as far as we have to go,'' he said.

Jeffrey Kessler, the chief outside counsel for the union, said he thought the grievance had been a long shot anyway. ''The arbitration was a little bit like a tie game and we took a 40-foot shot at the buzzer,'' he said. ''We missed, but we're still tied. We're still in the same place we were yesterday. Unfortunately, I think this is a bad decision for the fans because I think the league would have been more apt to reach an agreement quicker if the players had won.''

Stern sent a letter to Hunter yesterday and requested that he mail it promptly to his constituency. It contained an offer to meet, a three-part proposal and a guarantee that player salaries would rise 20 percent -- from $1 billion to $1.2 billion -- over the next four years.

The league is apparently trying to argue that it is not interested in trimming salaries so much as it is determined to bring contracts in line with total revenue growth.

But the union contends that the last time total salaries rose less than $50 million a year -- the average annual raise under the league's proposal -- was more than 10 years ago. To the players, the league's proposal would erase many gains made by the players in the last agreement, a deal that the owners say resulted in the players' making 57.1 percent of the league's total basketball-related income.

Stern voiced frustration that his dealings with the current union leadership had been less productive than with previous leaders, and Hunter answered by accusing league officials of harming the image of the game with what he called their ''hard-line bargaining approach.''

''The sooner the owners realize this and end the lockout, the better chance we have of avoiding enormous damage to the sport of professional basketball,'' Hunter said. ''Sadly, what the owners may not realize is that if they continue to antagonize the fans, the fact that the players may miss a few paychecks may be the least of their worries.''

Asked to elaborate, Hunter said: ''The product may suffer enormous, irreparable damage. If the fans get turned off, they may stay away, and the long-term losses may be much more severe. I don't think any of us want to kill the goose that lays the golden egg.''

Having canceled its first two weeks of games, the league will look at canceling another block of games next week.

Feerick took the full 30 days to issue his ruling, which ran 84 pages. It was the first significant N.B.A. case he has arbitrated since sharply reducing Latrell Sprewell's punishment for choking his coach last December, a ruling that angered the league and was considered a major victory for the players association. Feerick said his decision yesterday was founded on the basic tenets of Federal labor law, which states that employees do not get paid during a strike or lockout.

''The evidence is not sufficient to establish such a limitation on the Federal labor law right of an employer to lock out its employees in support of its bargaining demands in a collective bargaining negotiation following the termination of a collective bargaining agreement,'' Feerick wrote in his conclusion.

The league had indicated that if the arbitrator's decision went against it, an appeal would be filed in Federal court.

With 200 players not receiving their paychecks on Nov. 15 and talks at a standstill at least until the end of this week, talk of union decertification abounded among several agents yesterday, a process that would remove the union as the players' bargaining agent.

Photo: Billy Hunter, executive director of the players' union, said the lockout was antagonizing fans. (Associated Press)(pg. D4)