Bob Dandridge, who had told his Washington teammates they would win twice this weekend in Atlanta, fulfilled his prediction today.

Dandridge's brilliant 31-point effort was just enough for the Bullets to squeeze out a scintillating 120-118 overtime triumph against the determined Atlanta Hawks.

The Bullets assumed a commanding 3-1 lead in this Eastern Conference best-of-seven semifinal series going into game five Tuesday night in Washington. The Hawks will be a decided underdog, but there is nary a Washington player who believes the series-clinching win will come easy.

Atlanta, which refuses to quit even when logic says otherwise, twice faced overwhelming deficits today. The first came in the final minutes of regulation and the second at the end of overtime. Both times, the Hawks made remarkable comebacks, finally falling barely short in the extra period.

Washington survived on Dandridge's incredible pressure shooting, when everyone in the sold-out Omni knew he was going to get the ball, and on two downtown, fall-away, desperation jump shots by Kevin Grevey, who shot two for nine before those successive successes in overtime.

The Hawks had a clear-cut chance to win in regulation, but got fouled up by inability to ad-lib off their precise offense.

They had seven seconds to get off a shot to break a 109-109 tie, but did not. Guard Eddie Johnston stood at the top of the key with the ball and watched all the options in the out-of-bounds play unfold. The buzzer went off as he passed to a wide-open Tom McMillen in the corner, whose too-late shot missed, anyway.

Johnston also missed a short jumper with five seconds to go in overtime that would have tied the game. The rebound was slapped by Atlanta's Tree Rollins, then snatched by Washington's Wes Unseld. Time ran out as the ball fell to the floor.

Washington, which fell at home last Tuesday, temperorily losing the purported home-court advantage in the series, captured Friday night's game here by sprinting away in the fourth period to break a 17-game Hawk home winning streak.

Today, the Bullets had to overcome a 12-point third-quarter deficit and did, thanks to Larry Wright's 10 points, before turning to Dandridge as the man in the fourth.

When Dandridge couldn't quite end the game in regulation, the Bullets went into the extra period without Elvin Hayes, who had totaled 29 points and 17 rebounds.

Hayes fouled out with 14 seconds to go in regulation, but his loss was offset by elimination of four Hawks on personals: Steve Hawes (16 points) and John Drew (20) in regulation and Dan Roundfield (22 points, 17 rebounds) and Armond Hill (five points) in overtime.

In overtime, the Omni fans refused to let their players fold in the face of superior Bullets firepower. The Hawks ultimately were shut off by what Coach Hubie Brown called "bad shots, anyone would say they were bad shots."

But not for Grevey, the man who shot them.

"He makes them every time against us," Brown said. "What were they, 23 to 27 feet, maybe farther out?"

Grevey began his heroics with the Bullets ahead, 115-114.

Atlanta's tenacious defense cut off Washington's attack and the 24-second shot clock was almost exhausted when he unleashed a high-arching, wide-open bomb from the right side: 117-114.

After McMillen missed a running attempt, the Bullets again almost ran out of time before Grevey, this time deep on the right sideline, fired up and way over Terry Furlow. As the ball buried in the net for a 119-114 lead, the Bullet guard bounced along the floor twice and almost into the water cooler along the Washington bench. He was helped up by a bunch of excited teammates.

That should have been the game. But Atlanta, after calling time with 37 second left, had one more run in it. Johnson popped an eigth-footer and then the Hawks forced Tom Henderson into a travel call at half court. Furlow's 25-footer with 24-seconds remaining closed the gap to 119-118.

A Hawk fouled Henderson, this trip, as soon as he got over half court. He made the first free throw, missed the second and Atlanta had eight seconds to force another overtime. But Johnson's shot would not fall and Dandridge's prophecy came true.

"I could see in Bobby's eyes that he had done everything he could (by then) and I got a feeling they'd try to cut him off," Grevey said. "So someone else had to take up the slack. The first shot was nice but the second, I just felt it. I just felt I could do it again."

Dandridge had done almost everything humanly possible to end the game at 48 minutes. He posted 15 points, in the fourth period after sitting out much of the middle two with foul problems. Down the stretch, working against the taller, better-leaping Roundfield, he scored 13 of the Bullets' final 20 points and assisted on two other baskets.

This was Dandridge, the pressure-proof, supremely confident veteran, at his best. He tied the game at 90-the first time the count had been knotted since early second quarter.

He proceeded to feed Mitch Kupchak for a layup, sink four straight foul shots, intercept a pass and swish a one-hander, convert two more free throws and find Hayes for a dunk.

When Henderson followed moments later with a three-point play off a fine solo fast break against Hill, Washington held a 105-101 lead and only 1:42 remained on the clock. The contest seemed over, but the Hawks thought otherwise.

Two foul shots by McMillen preceded a Dandridge jumper over the outstretched arms of 7-foot-1 Rollins. Rollins answered with a dunk and Johnson caught the Bullets napping on defense by taking a long lead pass from Roundfield and putting it in to create another tie.

Grevey missed a wide-open short jumper from the corner and McMillen drew Hayes' sixth foul on the rebound. The ex-Maryland star made both attempts for a 109-107 Atlanta margin with 14 seconds to go.

The Bullets needed extra time-out for Unseld to get the ball in bounds, but when they finally did, there was Dandridge, driving on a mismatched Johnson and pulling up for a soft one-hander in the middle of the lane: 109-109. Johnson then messed up Atlanta's final possession and the game went overtime.

"One thing about this team, when we are down by 10 or 12 points, no one comes to the sidelines screaming and hollering," noted Dandridge, who made six of his last nine shots. "We stay calm. We have the type of players who get tough and get on the boards."

The Bullets, who had been outrebounded most of the series, picked off eight more missed shots by Atlanta did after intermission. They also had been shooting poorly, yet made 16 of their final 31. And they were nearly flawless from the line, converting nine of their last 10 free throws.

It took such a clutch performance to shake off the Hawkes in easily the best game ot the series. It was physical (66 fouls called) and intense but the players performed closer to their capabilities than before and the excitement in the arena was electrifying.

But despite a series of fine efforts by Atlanta, the Hawks find themselves with a nearly impossible task. Dandridge says there is a difference in the goals of the two teams.

"Atlanta is fighting for identity," he said. "We are fighting for a second championship. I think we are on our way to being a championship team, now that everyone is involved." CAPTION: Picture 1, Atlanta Hawkes are disappointed as clock shows no time left. Bullets won, in overtime, 120-118, for 3-1 NBA playoff edge; Picture 2, Tree Rollins (30) and John Drew (22) double up on Bob Dandridge (10), raising arms in path of his shot. This play helped make Drew one of the four Hawks to foul out of the game.