Washington's and Seattle's domination of the National Basketball Association likely will not extend into a third season.

Other hungry teams have served early notice that they must be reckoned with and that this shapes up as a wide-open, unpredicatble year for the pro game.

The Philadelphia 76ers have been good for the last three seasons; this year they appear to be great. They won their first eight games, not tasting defeat until Wednesday night in Atlanta.

The Portland Trail Blazers, despite serious injury problems, won their first nine starts by concentrating on defense.

The Milwaukee Bucks have won nine in a row and the word around the league is that they are the genuine article.

The Boston Celtics added Larry Bird, M. L. Carr and Coach Bill Fitch and have won seven of nine games, including four on the road.

The Los Angeles Lakers finally got some rebounding help for Kareem Abdul-Jabbar in Spencer Haywood and Jim Chones, and a leader in charismatic Earvin (Magic) Johnson. They have won seven of 10.

That Los Angeles and Philadelphia are doing so well is not that much of a surprise. Despite some glaring problems, each had a 47-35 record last season.

It is Milwaukee and Boston that have made the biggest turnarounds. Boston had the second-worst record in the league last season, 29-53, and Milwaukee was 38-44.

"Portland has a good ball club, but they've also had a favorable schedule," said Philadelphia General Manager Pat Williams, explaining the Blazers' fast start. "But they've lost two in a row now and are coming back to earth.

"Milwaukee is a different story, though. They have a lot of firepower and they are legitimate."

A key to the Bucks' success has been the return of power forward Dave Meyers, who was sidelined last season with a ruptured disk in his back. The Bucks had no adequate replacement.

"We're a little like Philadelphia on offense and Portland on defense," said Buck spokesman Bill King II.

Milwaukee is fourth in the league in offense, averaging 117.3 points a game, and 10th on defense, yielding 105.7.

King, accenturating the team's depth, points out that reserves have played 38 percent of the time and scored 35 percent of the points.

"That's not much of a letdown," he said. "So when your bench is producing like that, you aren't afraid to go to it."

The Bucks have been successful in getting the opposition to play their running game and the other team has been running out of gas late in the third quarter or early in the fourth.

The Bucks also have one of the best shooting teams in the league. Marques Johnson, who held out the entire preseason, started the first game and scored 28 points. He is averaging 22.7 and shooting 59 percent. Brian Winters, perhaps the premier long shooter in the league, is averaging 18.9 points and shooting 54 percent in addition to furnishing 5.1 assists a game.

Kent Benson is averaging 11 points and shooting 60 percent and Meyers is averaging 13.8 points and shooting 55 percent.

And the Bucks have the most productive sixth man in basketball in Junior Bridgeman.

The quintessential sixth man because he can play guard or forward, Bridgeman is averaging 21 points a game and shooting 54 percent.

Quinn Buckner, Winters' starting guard mate, still is shooting bricks, but offensive fireworks from him are hardly needed.

The Buck bench also seats Harvey Catchings, Richard Washington, Pat Cummings and top draft choice Sidney Moncrief.

"If we can play with the same intensity over the next couple of weeks, maybe we can start talking about labels like 'super team,'" said Johnson.

Some people already are doing it.

Dick Motta is one of the biggest praisers of the 76ers' prowess.

"I said after we played them that first game that they would win 60 games and I still believe that," the Bullets' coach ventured. "They have great personnel. They got rid of all of the players who weren't team-oriented and they're playing together. They don't have (Lloyd) Free, (George) McGinnis and (Joe) Bryant anymore. Chemistry is so important to a team and theirs seems to be just right, now."

"There are three basic reasons for our success," said Sixer General Manager Williams. "To begin with, we are a more mature unit. Guys have really been through the caldron here. They've taken a lot of heat for not winning and it's toughened them and made them stronger.

"Secondly, everyone knows what's expected of them and they are comfortable in their roles. That just wash't the case before. All the petty jealousies we had in the past have been eliminated. And, thirdly, we've been healthy."

There is, of course, another reason the 76ers are playing so well -- they have the players. They start a 7-foot-1 forward in Caldwell Jones and perhaps the strongest man in the league at center in 6-11 Darryl Dawkins. They have one of the game's top shooting guards in Doug Collins, one of its most promising young playmakers in Maurice Cheeks and the imcomparable Julius (Dr. J) Erving at the other forward.

"Doc is in better shape than ever before and he knows everything revolves around him," said Williams.

Erving, off to his best start ever, is averaging 28 points a game.

The Lakes got a big scare when Johnson twisted his knee a couple of weeks ago. It was at first feared he had torn ligaments and would be out six weeks, but he missed only three games.

The 6-8 Magic enables Los Angeles to move Norm Nixon to shooting guard while Johnson provides the big defensive guard they have lacked.

And when Abdul-Jabbar is happy, he plays well. And when he plays well, he probably is the most dominant player in the league.

Despite the fast starts in Philadelphia, Milwaukee, Portland, Los Angeles and Boston, there is still some reserve in those places. They know it is a long season.

"I care about what is going on in the middle of March," said Williams, "and I'll tell you one team I know will be there and probably playing better than anyone else: the Bullets. They're starting slow and playing it cool, but when it really counts, they'll be ready."