The Bullets needed a controversial blocked shot by Elvin Hayes in the final 32 seconds yesterday to survive a desperation playoff gamble by the San Antonio Spurs.

The block, followed by two Charles Johnson foul shots with 11 seconds to go, gave the Bullets a 98-95 victory before 13,549 fans. The Bullets took a 3-1 lead in this best-of-seven NBA quarterfinal series.

But until Hayes batted away a driving shot by George Gervin, the Spurs were on the verge of returning to San Antonio tomorrow night for game five with the series evened at two wins apiece.

San Antonio had not been shooting or running well the previous two games, so coach Doug Moe abandoned the run-and-gun tactics that won 53 games this season (third highest in the NBA) and went with a patterned eat-it-up offense.

The move, coupled with a decision to start Mike Green instead of Coby Dietrick, unnerved the Bullets, who got off to a horrid start and never led until Larry Wright put in a layup with a minute remaining in the game.

However, the Spurs were never able to go ahead by more than seven points and this failure to put away Washington when they had the chance ultimately led to their downfall.

"We didn't adjust really well to what they did," admitted Bullet Coach Dick Motta. "They had us on the ropes the whole way but we hung in. I knew they'd adjust, but nor that much. It had to be out of desperation."

Whatever the reason, the change by San Antonio brought the strategy in the series full cycle. The supposedly slow musclemen from Washington now were trying to run while the high-speed Spurs were playing the Bullets' patterned-offense game.

With 90 seconds to go, it appeared the Spurs, approach had things under control. The unflappable Gervin, who had 35 points, was protecting a 93-90 lead by driving past whichever Bullet tried to guard him. He wasn't missing and Washington wasn't catching up.

But Motta went to what he called "our phase two" defensive plan and switched 6-foot-6 Bobby Dandridge onto the 6-8 Gervin. After Hayes, who had 23 points, put in a rebound of a Johnson shot, Dandridge forced Gervin to take an off balance six-footer that hit the side of the rim.

Washington immediately ripped off only its ninth fast break of the day. Johnson drove down the land and handed off to Larry Wright, who had a bad angle to the right of the basket.

"I would have liked the ball earlier but when I got it, I had to shoot it despite the bad angle," said Wright. "I know I could outjump (Louie) Dampier.If he was going to block a two-footer, he'd have to make a great play."

Dampier went for the block, missed and fouled Wright as the ball went in. But Wright missed the free throw and Hayes fouled Bill Paultz in the scramble for the rebound.

Paultz sank both foul shots to put the Spurs ahead, 95-94. With the Capital Centre crowd standing and screaming the Bullets countered with a dunk by Hayes, who was set up by a fine lob pass from Wrights.

San Antonio called a timeout with 41 seconds on the clock, but there was no mystery to what the Spurs were going to do. They got the ball to Gervin, who went on one on one against Dandridge at the top of the ky.

During the timeout, Motta told Hayes to guard Paultz and Wes Unseld to take Green. "That way Elvin would be in position to help out defensively and Wes could rebound," said Motta.

The switch paid off. Gervin got past Dandridge and put up a clothesline one-harder from 10 feet out. Hayes, who was positioned under the basket, stepped out and batted the ball almost to half-court, where Damper picked it up and then tossed a pass into Dandridge's hands.

The Spurs fouled Johnson with 11 seconds left and he made both tries for the winning margin. The Spurs had one more offensive attempt, but Dampier missed a 15-footer and time ran out.

Moe said he felt the Hayes block was goaltending, a view shared by some of his players. But referee Jake O'Donnell said "the ball was still on its upward trajectory. It hadn't started down at all. It wasn't goaltending."

That's how Hayes saw it too.

"I've been blocking shots for 10 years in this league and I know it wasn't goaltending," he said. "It was basically a straight-line shot. They had run the play five times before and we were prepared for it. The ball was far away from going in. It never got close."

Dandridge, who was an interested spectator by the time Gervin shot, was just thankful "the refs decided to make a hell of a call at the point. I felt it was goaltending when it happened but I'm glad it wasn't."

Besides scoring 24 points, Dandridge had the unenviable task of guarding Larry Kenon and then Gervin, the Spurs best scorers. Kenon, who is not suited for a slowdown game, scored only 10 points and did little to stop Dandridge's offensive output.

"The one thing their lineup change did," said Motta, "was it forced us to put Dandridge on Kenon (instead of Hayes). It was a good matchup for us, and Bibby was able to isolate Kenon at the offensive end and work on him."

Washington's three front-court starters combined for 64 pointes (Unseld had 17), but the Bullet guards couldn't hit effectively from the outside and relieve the pressure created by Antonio's swarming, double-teaming defense.

"If we could have had better outside shooting, we might have pulled away," said Motta. "They were able to jam things inside. We got just enough fast breaks to stay in the game. If we hadn't been able to run even the little bit we did, it might not have turned out the right way for us."

For Moe, the defeat was escpecially hard to take. It put the Spurs in a sudden-deah situation after they fired perhaps their best possible surprise at Washington.

"If we had been shooting and running well, we wouldn't have had to change," he said. "We had to do something. It almost worked."

But it didn't and now the Bullets have to win only one of the next three games to wrap up the series.

"For a club that isn't supposed to be this good, we aren't playing badly, are we?" said Hayes with a smile.