The National Football League Players Association struck early this morning for the second time in six seasons, jeopardizing the rest of the league's season after only two weeks of games.

Club owners will try to field new teams to continue the schedule Oct. 4-5. Games scheduled next Sunday and Monday would be delayed until after the regular season.

"I don't know what you call NFL quality," General Manager Bobby Beathard of the Washington Redskins said. "I'm concerned about putting a team on the field that can win games. Our intent is to sign more than 45 players. There are going to be some good players."

Gene Upshaw, executive director of the NFL Players Association, announced the strike during halftime of the New England Patriots-New York Jets game in East Rutherford, N.J., which was televised nationally. The strike deadline, originally set at 12:01 this morning, did not affect the game, which ended at 12:30 a.m.

Upshaw, appearing from Washington on TV at halftime announced: "As of midnight tonight, the players of the National Football League will be on strike again. None of us wants this, not the players, not the fans, not the owners, and that's really, really sad."

He said he had "initiated a move to a person with some authority." He did not say who, although earlier he had called on the NFL commissioner, Pete Rozelle, to intervene. Rozelle, though, said earlier Monday he didn't plan to get involved.

Upshaw has also called for the intervention of any owner "who can make the deal." Late last night he said he will bypass the league's chief labor negotiator, Jack Donlan, and take the squabble to someone else in management. He said Donlan lacks authority to make a deal to end the strike.

"The only time we'll ever have true negotiations is when someone with authority on the other side enters into the process," he said.

Donlan also appeared on TV at halftime during the game, reiterating management's position.

The day passed with no new negotiations or conversations between the chief negotiators.

"As far as we're concerned, the strike is on," said Philadelphia Eagles player representative John Spagnola yesterday afternoon as players began clearing out lockers and the union began distributing signs and instructions for picketing.

Upshaw announced that striking NFL players and members of other unions will begin picketing the NFL's 28 practice facilities Wednesday. That is the same day the owners are expecting replacement players to begin practicing for the intended resumption of the season Oct. 4. Players on some teams, including the Washington Redskins, said they will begin picketing today.

A Washington Post-ABC News poll over the weekend showed that six of every 10 respondents who said they are football fans plan to watch telecasts of these games, even though the same amount called using the substitute players "a bad idea." About one in two respondents said they side with neither players nor owners. {Details, Page C1.}

The Management Council's executive committee met yesterday in New York, reportedly to finalize plans for continuing the season by using players cut in training camp, veteran free agents and any union members who decide not to strike. They also formulated a leaguewide ticket refund plan.

Tampa Bay Buccaneers owner Hugh Culverhouse said owners are wary of losing fans. "Our concern is with the fans coming back strong," he said. "We're coming off a flat year in TV negotiations, and there's not a lot of money; no room for significant movement."

Each team would lose $1 million a week if the union shuts down the league, according to Mike Duberstein, the NFLPA director of research who said he based this estimate on figures provided by the Management Council. The union estimates player losses would average $15,000 per man a week.

Potential losses or profits for individual teams cannot be accurately projected because of the uncertainty of ticket refunds and TV rights-fee rebates if play continues during the strike.

Earlier, Upshaw told the Associated Press: "I have something up my sleeve I'm going to reveal later." Pressed later, he said: "I have nothing up my sleeve but my arm," then went on to say, if the sides met again, "I think you could hammer out a deal in a matter of a day."

Little has been accomplished in five months of negotiations. Each side claims the other doesn't want to negotiate, but the owners say the only roadblock to a settlement is the players' desire for more freedom in moving from one team to another. The union says free agency is one of seven issues preventing settlement.

There were conflicting reports on how many players might cross the picket lines and try to play. Redskins owner Jack Kent Cooke said his team had signed about 40 players, a figure disputed by Upshaw, who said the Redskins had signed 12. A league source said many teams have verbal commitments but will not know who is available until Wednesday.

The Management Council, which, before the strike, declined comment on contingency plans, is expected to announce today that franchises that cannot field strike teams will forfeit those games and face fines and/or loss of draft choices.

The attempted continuation of the season with replacement players is one aspect in which the strike will differ from that of 1982, when the league was idle 57 days.

The owners' success at conducting these games is seen as a major factor in how long the strike lasts and which side ultimately prevails. Upshaw and other NFLPA officials predict virtual 100 percent solidarity among its 1,600 members. The owners, sources said, are counting on the players breaking rank, especially if management can field teams and continue the season.

At least two teams, the Redskins and Chicago Bears, voted again yesterday to strike. The vote was unanimous for both teams, according to player representatives. The New England Patriots and San Francisco 49ers will vote today.

The threat of violence on the picket lines escalated yesterday.

"Any action they take is a risk," Upshaw said yesterday in one of his most militant statements to date. "They will be crossing the picket line at their own risk."

In Buffalo, Bills nose tackle Fred Smerlas said: "And if the scabs come in, they're dead men. Just look at it this way, if the truckers went on strike and they had scabs come in, how many new lily pads would there be in Lake Erie?"

The owners are expected to station extra security personnel at practice sites and hotels housing substitute players.

The owners are expected to get some indication today about the solidarity of the union. At least five or six teams, including the Los Angeles Raiders and the Philadelphia Eagles, postponed their normal Monday team meeting and film session until today.

"They changed it so they can see who's striking and who isn't," said Dick Berthelsen, the NFLPA's general counsel. "They want to count them as a strikebreaker even if they're just picking up their paychecks."

In a statement, the Management Council said a decision by an arbitrator yesterday in a grievance filed by Major League Baseball Players Association over free agency in that sport "only strengthens our commitment to a settlement without the unrestricted free agency demanded by the NFLPA."

Staff writer David Aldridge in New York contributed to this report.