With Kevin Grevey finally gaining his shooting eye and Elvin Hayes patrolling the inside like his idol, Bill Russell, the Bullets scratched out one good quarter of basketball tonight. But that was enough to regain control of this slash-and-back playoff series against Atlanta.

Despite being held to its season-low point total, Washington showed enough playoff poise in the fourth quarter, mainly thanks to Grevey and Hayes, to snap the Hawks' 17-game Omni winning streak, 89-77.

The triump gave the Bullets a 2-1 lead in the Eastern Conference semi-final round and wiped out the advantage the underdog Hawks gained by beating Washington Tuesday night in Capital Centre.

Game four will be played here Sunday at 1:30 with the two teams returning to Capital Centre for game five on Tuesday.

This series has yet to produce a pretty game, one that would satisfy basketball purists. And this one was the roughest yet, with neither club shooting or playing well for 36 minutes.

But the Bullets finally shrugged off 25 percent markmanship and a hugh rebounding deficit through three quarters to show some of the form that won them last year's NBA title.

Grevey, popping away from the outsider for the first time in the series, contributed three baskets during a 16-4 outburst early in the fourth quarter that rallied the Bullets from a 69-67 deficit and gave them an 83-73 lead.

Once Grevey loosened up the Hawks defense with his perimeter jumpers, everything else fell into place. The Bullets began running, the offense began functioning and Hayes refused to let any Atlanta players get near the basket for easy attempts.

Grevey finished with 14 points, including eight in the fourth period. Hayes led with 19 points and 14 rebounds, a stark contrast to his 10-point, eight-rebound effort in game two. But during thos crucial moments when the game was still undecided, his worth could not be measured in points but rather in how he intimidated his forces, who were just two of 12 during the spurt.

"I had one bad game," Hayes said afterwards, "and people get down on me. "I'm a pro. I wasn't going to have another bad one. They shouldn't forget what I did last year. I wanted this one bad tonight, real bad."

The Bullets won this one despite 15 points from Bob Dandridge, who had been averaging 33 for the series. But Dandridge was intent coming into the contest to get more teammates involved in the offense and his intentions ultimately worked out. Six Bullets had at least nine points and Atlanta wound up not knowing who to cover.

The Hawks hurt themselves considerably with horrible shooting (37 percent), 20 turnovers (to Washington's 10) and a lackluster final 12 minutes.

The Hawks' two main scorers, John Drew and Dan Roundfield, "went into the tank" in the fourth, according to Coach Hubie Brown. Roundfield finished with 11 points, none after the third, and he missed four straight shots while the Bullets were forging ahead. Drew avoided foul trouble for the first time in the series, yet was just six of 18 for the half and had only four points in the fourth.

Only Wayne (Tree) Rollins, who plays bigger than his already hugh 7-foot-1 height, turned in a consistent game for Atlanta. His 14 rebounds and five blocks frustrated Washington during the first part of the second half and seemed to give the Hawks second life after they failed to capitialize on a 41-26 intermission rebounding advantage.

The Bullets had wanted to imporve their fast break, had wanted to improve their fast break, dominate the boards and get balanced scoring, things they had not done well in the first two play-off games.

But Washington was outrebounded, 31-15, in the first quarter, and finished the period with 16 points, that included only two fast transition baskets.

But Atlanta was performing just as poorly; allowing the Bullets to actually go up a half, 42-39, when Wes Unseld rammed in three straight baskets, then Hayes duplicated that feat and Dandridge scored his first points of the game to end the second period.

When Atlanta finally broke out of the doldrums early in the third period and used a 12-2 spurt to grab a 57-48 lead, the Omni fans were on their feet, screaming for another notch on that winning streak.

But three straight Bullets fast breaks, then a 15-footer from Grevey knotted things at 61 going into the final 12 minutes.

"I looked up at the score and I couldn't believe we were still tied," said Grevey. "Not the way we had been playing."

Washington had stayed in contention because of its tenacious defense, which constantly was knocking balls out of the hands of the hawks. Now it was time for the offense to finally come alive.

Grevey began things on a layup for a 69-all tie. Terry Furlow was slapped with a technical, which Dandridge converted. Then Mitch Kupchak, who had seven of his nine points in the quarter, sank two free throws. A fast-break layup by Tom Henderson off a Grevey feed put Washington up, 74-698 beofre Rollins put in a rebound.

That only served to ignite another Bullet surge. Kupchak, who had been stuffed twice by Rollins, got a rebound of his own shot, faked the Atlanta center, sank the basket an was fouled for a three-point play. Moments later, Grevey banged in a wide-open 20 footer, then he followed with an 18-footer and Dandridge ended things with a driving one-hander over the jumping Rollins.

Washington now was up, 83-73, with 1:44 to go and the Bullets bench could celebrate. Atlanta could just look at the numbers: that horrible two-for-12 shooting, three turnovers and enough mental errors to foul up Brown's computer-like coaching tactics.

Hayes did his damage by double-teaming underneath the boards. Whenever Roundfield would make a move on Unseld, Hayes would be standing behing his teammate, leaping high as he could and forcing the Hawks forward to loft his shot. Then either Hayes or Unseld would still be able to get the rebound.

In the fourth, the Bullets finally dominated those crucial boards, limiting Atlanta to one shot on almost every possession. That was hardly the case earlier in the game, when it seemed every loose ball was being picked off by Atlanta.

"On Tuesday, my body was going every different direction," said Hayes. "My head was over there, my middle was somewhere else. I just couldn't get it together. But tonight was different. I felt I was in a rhythm. CAPTION: Picture Hawks John Drew leaps in vain effort to snatch ball from Bob Dandridge (10) as Tom Henderson watches third-quarter action. UPI