Elvin Hayes and Bobby Dandridge got playoff fever yesterday, combining for 61 points to swat the pesky Atlanta Hawks, 103-89, in the opening game of this Eastern Conference semifinal series.

The pair contributed 37 of the Bullets' 57 second-half points, including many in the final 12 minutes as Washington erased a 76-71 lead Atlanta had built through three periods.

A boistrous Capital Centre crowd of 15,721 saw the defending NBA champions hold the Hawks to 13 points the last quarter and turn what had been a tenacious, scratch-and-claw struggle into a belated romp.

The Bullets did have a scare. Early in the fourth quarter Charlie Johnson took a charge and crumbled to the floor. He got up holding his knee but the injury was diagnosed as a bruise and isn't considered serious.

Don't be misled by the final score. The Bullets had all they could handle with hustling Hawks, who did everything necessary to win except control Washington's dynamic duo up front.

But few teams can. Hayes and Dandridge gave notice yesterday they won't let down in this years's championship chase.

Hayes, fired up after Dan Roundfield blocked two of his first-half shots, punished the Hawks inside for 31 points and 15 rebounds while intimidating them on defense. He made 11 of 24 shots, but was seven of 12 after intermission.

Dandridge, coming off a two-day bout with flu, tossed up his usual assortment of running one-handers, graceful jump shots and smooth drives. He finished with 30 points, 12 in the fourth period when Coach Dick Motta thought he might tire.

On an afternoon when their offense was not functioning full throttle, the Bullets gave the ball to the two forwards as much as possible. Only one other Bullet, Kevin Grevey, hit double figures.

Atlanta was handicapped, too. Leading scorer John Drew, in foul trouble most the way, scored only seven points. Backup center Tree Rollins, who normally plays well against Washington, had foul difficulties and couldn't score at all.

The Hawk guards kept their club in the game for three periods with fine penetration. That led to layups or open shots, especially for Roundfield. He had 20 of his 24 points in the first 36 minutes.

But the Bullets' church-mouse guards, Larry Wright and Johnson, tightened up defensively in the fourth, forcing Atlanta to shoot outside. At the same time, Washington overplayed inside and clogged the middle.

The Hawks didn't adjust and went cold. After the game was tied at 85, they made only one of their last 10 shots the final six minutes and their carefully conceived game plan fell apart.

Washington, which had wanted to run all afternoon but couldn't, suddenly turned on the afterburners.Wright, perhaps the quickest guard in the league, started talking outlet passes from Hayes and Wes Unseld (11 rebounds, five assists) and beating Atlanta down court.

Wright's layup off an Unseld feed gave the Bullets an 87-85 lead and that set up Washington's outburst. Dandridge blocked Jack Givens' shot at the other end and the unflappable forward then banged in a jumper over Drew, who had just returned to the game.

Drew, who had only three points after the first period, tried to repay Dandridge with a drive across the middle but found himself in the air with nowhere to go. When he tossed away the ball, Unseld swatted it to midcourt, Wright picked it up and drove to the basket.

Wright waited until the last second and passed to Grevey, whose layup was batted away by Rollins. But the block was called goal tending and the Bullets had another basket.

Atlanta was feeling the pressure. The noisy crowd supplied part of it and gave the Bullets a long, standing ovation at the beginning of the fourth period, despite their 76-71 deficit.

Eddie Johnson, who failed to score in the last quarter after having 14 points through three, couldn't sink an open eight-footer. Unseld fired off another long pass to Wright, who again fed Grevey. But Grevey was too far beneath the basket when he released the shot, and missed. Hayes roared in, picked off the rebound and scored.

Now the Centre was in uproar. Atlanta Coach Hubie Brown, as always pacing the sidelines, yelling at his players, tried to calm them. The Hawks responded by setting up another good shot for Johnson but he failed on a shot jumper. Drew had a second try, but it, too, looked like a brick heading to the basket.

The Bullets could taste victory. On their next possession, Dandridge got the ball to the left of the basket and Drew, perhaps symbolically, yelled for help. It didn't come and Dandridge popped in a shot from the corner.

When Dandridge finished off the splendid 12-0 spurt with a running onehander for a 97-85 lead, everyone but Brown knew the game was over.

But none of the Bullets discount Atlanta in Tuesday night's second contest.

"You've got to give them credit," Wright said. "I don't think we can ever blow them out. They keep coming and coming and coming."

Motta thought Atlanta's second-quarter comeback from a 42-30 deficit would set the tempo for the rest of this best-of-seven series. Every time Washington wanted to relax, there were the Hawks, double-teaming and overplaying and causing 16 turnovers in the first 36 minutes.

But just as the Bullets tightened their defense in the final period-"It was perfect defense, I'm sure the films will show that," Motta said-they also steadied their ball handling. They didn't have a turnover the last quarter while Atlanta, a newcomer to playoff fever, had four.

It wasn't a pretty game, but no contest involving the Hawks is. It came down to Washington's superior inside muscle and its coolness under pressure.

"We wore them down inside," Hayes said. "We kept driving it to them until they finally collapsed. No one is capable of pounding away like that with us." CAPTION: Picture 1, Larry Wright finds his path to the basket blocked by Dan Roundfield, so he passes to Bobby Dandridge, who gave Bullets 89-85 lead in NBA playoff opener against Atlanta at Capital Centre. By Richard Darcey-The Washington Post; Picture 2, Wes Unseld waits for Dan Roundfield to come down before setting up Bobby Dandridge's basket. Photos by Richard Darcey-The Washington Post; Picture 3, In final minutes, Steve Hawes of Hawks makes certain Elvin Hayes scores only from foul line.