They have survived challenges by upstart Atlanta, which was motivated by a pushy coach, and from stubborn San Antonio, which was motivated by pride.

They have frittered away the home-court advantage in two straight series, been on the brink of elimination from the playoffs in three different games and been so unpredictable that many in their legion of emotional fans probably are developing ulcers.

Now the roller-coaster Washington Bullets must overcome perhaps the most difficult incentive of all-revenge-if they are to beat the Seattle SuperSonics and win a second straight NBA title.

The SuperSonics are still smoldering over last season's seven-game defeat at the hands of the Bullets in the league finals.Starting with today's 1:30 p.m. opening game of the championship round at Capital Centre (WDMV-TV-9), Seattle hopes to make amends for that failure.

And the Sonics couldn't be catching Washington at a better time. The Bullets were still walking around in a daze yesterday, wondering how in the world they managed to rally late in the fourth period Friday night and beat San Antonio in Game 7 of the Eastern Conference championships.

"I don't think we know how we pulled it off," said Coach Dick Motta. "I want to look at the films again. I guess it just says something for determination and not giving up. You've got to admire them for that."

But now Motta has to make sure his players are aroused sufficiently to compete with the Sonics. Otherwise, the Bullets, who are trying to become the first team to repeat as champion in 10 years, will find themselves once more without the benefit of the homecourt advantage.

"We can't afford to lose that homecourt advantage anymore," forward Elvin Hayes said. "We can't let the momentum let down like we did in the first two series. We must win the first two games here."

This will be by far Washington's most difficult challenge. Seattle is a solid, talented, well-coached club that can match the Bullets on the boards, has an edge in the back court and feels it has become stronger with a year's experience.

It also is a slightly different team from the one that pushed the Bullets so hard last season.

Gone is shot-blocker and rebounder Marvin Webster, opting for the N.Y. Knicks. But with Jack Sikma switching from forward to center and Lonnie Shelton moving into a front-court spot, the Sonics run better and are more physical underneath.

"We are a better team than last year," said Coach Lenny Wilkins, who kept his club on top despite a regular-season injury to center Tom LaGarde. "We approach the series much more confident."

Seattle's offensive strength still lies in the guards. Gus Williams, Dennis Johnson and Fred Brown supply the firepower, although Sikma is a constant threat inside with his uncanny turnaround jumper.

And without injured Mitch Kupchak, the Sonics also have more flexibility up front than Motta. Wilkens likes to go at times with a big front line of Sikma, Shelton and veteran Paul Silas.

Motta normally would counter with Kupchak, Hayes and Wes Unseld, but now either Greg Ballard or Bob Dandridge will have to handle Silas, still an accomplished offensive rebounder.

Although he would not commit himself, Motta also probably will employ Dandridge at guard during the series so that both Ballard and Dandridge can be in the lineup at the same time. The Bullets' use of Dandridge at guard was the key to their winning the last three games against the Spurs.

Seattle is convinced its guards can dominate their Bullet counterparts and, as long as the Sonics can match Washington around the basket, they can control the series.

"I think it's going to be an inside game," Silas said. "Whoever is the best inside is going to prevail. I think we can match their board strength.

"They are a great offensive-rebounding team and they have two great scorers inside. They run very well but not exceptionally well. Maybe their main weakness is the transition game, because we do have a lot of speed and quickness and we can get up and down the court better.

"We'll look to exploit their guards as much as possible. But we still have got to go inside if we want to win."

Washington, meanwhile, feels it must rebound well and get help from its bench to compete successfully in the series.

"You can't run if you don't have the ball," Motta said. "We're at a disadvantage without Mitch but our bench gave us a lift last year and we need that again this year.

"I see this series going seven games. Both teams are glad to be here, just to prove that last year wasn't a fluke. It's going to be physical and I think the fans are going to like it."

Last year, when the two clubs met for the championship, the series was considered less than artistic by many critics, who had hoped for a Philadelphia-Portland rematch. Seattle was a Cinderella bunch while few thought the late-finishing Bullets were as good as they looked.

Although the confrontation produced exciting, hard-fought basketball, television ratings were disastrous and the Bullets felt no one respected them for capturing the crown.

Things have changed. The teams had the league's two best records in the regular season and dominated the standings from the start of the schedule. They split their four-game series, each winning away from home, and were picked from the beginning of the playoff, to ultimately wind up facing each other for the title.

Seattle cruised through its conference semifinal series with Los Angeles, but came within a game of being eliminated by Phoenix in the West final before beating the Suns on their home court, then winning the seventh game Thursday night in the Kingdome.

But Seattle's path to this round has been a lark compared with Washington's struggle. Only the play of the Bullets up front, especially Hayes and the remarkable Dandridge-along with lifts from Ballard and Unseld-have kept them from being eliminated.

At least Motta's team won't have any surprises against the Sonics. The matchups are predictable, at least at the start: Dandridge against John Johnson, Seattle's top assist man; Hayes vs. strongman Shelton, who is less prone to fouls lately; Unseld vs. the steadily improving Sikma; Henderson against Williams, the cat-quick explosive scorer, and Kevin Grevey against Johnson, the defensive whiz who also is a constant board threat.

Johnson became a star with his play in last year's series. He blocked so man Grevey shots that the Bullet guard became gun shy and wound up being replaced for long stretches by Charles Johnson. Gus Johnson is so quick he roams around the floor, double-teaming, grabbing rebounds swatting shots while also covering his assigned man.

Henderson, who missed all nine shots Friday night, feels comfortable guarding Williams, the Sonics' No. 1 scorer. The Bullet playmaker also realizes he must help his team control the series' tempo.

"We have to play our game and not let them run wild," Henderson said. "If we do that, we'll be okay." CAPTION: Picture, Elvin Hayes, the costar with Bob Dandridge in dramatic win Friday, will match up his skills with Sonics today. By Richard Darcey-The Washington Post