Atlanta reduced Washington to a one-man offense last night, then stunned the Bullets with a dramatic fourth-period burst for a 107-99 upset at Capital Centre.

The Hawks' emotional triump which shocked a sellout crowd of 19,035, tied this Eastern Conference semifinal round at 1-1. But it also gave the winners a chance to take a commanding lead in the series which moves to Atlanta for games three and four this weekend.

Washington entered the contest knowing it had to win to keep the home-court advantage. But atlanta completely frustrated the Bullets by holding Elvin Hayes, who fouled out with 6:39 to play, 10 points - 21 sagging, aggressive defense.

Only Bob Dandridge, who finished with 36, could score consistently for Washington, and even he was cut off early in the fourth period when Atlanta went on a 16-4 spurt that broke open the game.

Atlanta made its charge with the score 83-all. By the time the Hawks had finished, five players had contributed points. The Bullets, meanwhile, had made only two of 14 shots and suddenly this series had taken an unexpected turn against the defending NBA champs.

This was tenacious, unselfish Atlanta at its best. The Hawks received at east four points from 10 men and had six players in double figures, led by Dan Roundfield and Eddie Johnson, both with 17. Urged on by Coach Hubie Brown's constant screaming, they refused to let Washington work the ball down low where the Bullets had domintated game one, when Hayes and Dandridge scored 61 points.

Atlanta had success dropping a guard inside every time Hayes touched the ball. When the Bullet forward tried to dribble, one of the little Hawks would be there, slapping, making it almost impossible for Hayes to get off a clean shot.

hayes wound up making only five of 17 attempts.He picked up eight rebounds and had seven blocks in 32 minutes but scored only two points in the final period.

Washington, however, had expected Brown to make defensive adjustments to try to control the Bullets' talented forwards. The Bullets failed to pick up the changes and their inability to run their offense with any consistency contributed heavily to their downfall.

"Elvin got into foul trouble but other people have responsibilities," Dandridge said of the Bullets' one-on-one tendencies. "Maybe Elvin and I should take fewer shots. We are more effective as a team when the points are more evenly distributed, as indicated by our regular-season statistics."

Atlanta also kept the game's tempo slow, refusing to let the Bullets run as much as they did in the opener. Even when the Hawks full behind by five in the third period, Brown screamed for them to walk for an open shot.

"Hubie made them control the tempo," said Dandridge, who twisted and turned-well enough to make 13 of 20 shots. "He didn't let them get into a running game. He kept them in striking distance even when we got a lead. He made them slow it down and go to their patterns.

"They may have the best home record to boast of (17 straight wins in the Omni) but we have the best road record. I think we can go in there and win twice."

One telling weakness for the losers was the lack of scoring from the usually potent bench. Larry Wright finished behind Dandridge with 14 points but reserves Mitch Kupchak, Charles Johnson and Greg Ballard were just four of 17 from the floor, combining for eight points.

The Hawks bench was much more effective. With center Wayne Rollins dominating inside and forward Tom McMailen poppingfrom downtown, the Atlanta reserves had 45 points, 10 in the final 12 mintues.

Brown also helped his club by changing defensive assignments during the game. After Dandridge, who was magnificent again despite great pressure, got off to a quick start against John Drew, Brown switched Roundfield onto him and began guarding Hayes with his centers, Steve Hawes and Rollins, and Tom McMillen.

Although Dandridge wasn't bothered by the switch, the new matchups worked. Atlanta was able to hold its own on the boards, something it was not able to do in the opening game, and Rollins and McMillen both turned in fine efforts.

The game might have set some sort of NBA record for offensive fouls. The more the Bullets tried to work inside and get good position around the basket, the more they were called for pushing off, or charging.

Three of those charges came during the crucial early minutes of the fourth period, after the Bullets had spent three quarters trying desperately to shake off their determined foes.

The outburst started innocently enough when Roundfield, who scored 11 of his 17 points in the second half, sank alayup. Washington missed three shots at the other end before Wright was called for tossing an elbow. On Hayes' fifth foul, Roundfield scored a free throw.

Wes Unseld, who had 13 points and 10 rebounds,tossed away a pass and reserve Terry Furlow drove down the court for a dunk and an 88-83 lead.

The fans could sense the turn in the game and even when Unseld swished a jumper, the uneasiness didn't cease. And for good reason: the Hawks were in charge. They got a basket from the struggling Drew, again hindered by fouls, and, after Washington couldn't sink three shots and threw away another pass, Johnson drove by Wright for a three-point play.

The Bullets, hanging by their fingertips, soon were falling for good. Kupchak broke the scoring drought with a layup when Rollins was called for goal-tending. But a Rollins dunk, an offensive foul on Dandridge, a Roundfield drive and two free throws by Rollins had Atlanta easing in, 99-87.

Washington shot a miserable 35 percent in the final 12 minutes, but even that figure is misleading, since the Bullets made three of their last four. The Hawks answered with 73 percent marksmanship and the kind of offensive confidence that allowed them to run the shot clock down to four or five seconds consistently before scoring.

"We didn't have that apark," said Bullet coach Dick Motta. "We were either standing around too much or they were playing great basketball. I don't question the calls. But nine offensive turnovers (charges) are not typical for the Bullets."

hayes never could shake off his horrible start. He missed seven of his first eight shots and his only two first-half baskets were on rebound follows. He made just one long-range, turnaround jumper for the night, which might be a career low.

"They kicked us good," said Motta. "They played well, they executed well. Now this playoff is a lot like Seattle (last year). But I don't think the team is discouraged or disappointed." CAPTION: Picture 1, Wes Unseld (41) of Bullets goes high against John Drew of Hawks in backboard battle, with Bobby Dandridge waiting at right. Unseld led all players last night with 10 rebounds. By Richard Darcey-The Washington Post; Picture 2, Double-teaming Hawks attempting to block Charles Johnson's jumper are Terry Furlough, left, and Dan Roundfield. By Richard Darcey-The Washington Post.