The Bullets combined outstanding performances from Elvin Hayes, Bob Dandridge and Greg Ballard with a lineup change that caught San Antonio off guard tonight to ruin the Spurs' Eastern Conference championship victory party, 108-100.

The triumph, before a full house of stunned Spur fans, tied up the best-of-seven series at 3-3 and forced a final game Friday night in Capital Centre. If the Bullets win that home test, they will be only the third team in league history to override a 3-1 playoff deficit.

This was a game San Antonio thought it would win on the strength of its home-court advantage and the shooting of George Gervin.

But the Bullets reached deep into their bag of playoff experience and came up with a scintillating team effort that shackled the Ice Man and produced their best-balanced scoring of this hard-fought round.

Six Washington players registered at least 12 points.In the final quarter, when the team broke from 82-all to gain control, points from five Bullets shot down the Spurs, including 10 from the fast-closing Dandridge.

"We've come from a deep hole to level ground," said Hayes, a dominating force underneath the baskets the whole night. "The determination and desire will be tremendous Friday."

Gervin, finally removed from the contest with 2:24 remaining from the bunch of wild shots, was held to 20 points-11 under his series average. Dandridge took over guarding him about four minutes into the last quarter, in which Gervin scored only four points.

Without the Ice Man's normal production, the Spurs were gunfighters firing blanks. They tossed up hods full of horrible-looking attempts, which left things wide open for the eager Bullets.

Hayes, making up for Wes Unseld's foul problems, delivered 25 points, including 16 in the second half, plus 14 rebounds, five assists and six shot blocks.

Dandridge, despite a poor shooting night (eight for 24), was stellar on defense while providing eight assists and 20 points. And Ballard, continuing a string of fine relief work in the series, contributed 12 rebounds and 19 points, eight in the last 12 minutes.

Ballard's points were made more significant by the fact that he was being covered in the final period by Gervin, who was loath to block him off the boards. So the aggressive Bullet forward came up with two offensive rebound baskets, then a wide-open jumper from the corner while Gervin stood at the foul line and watched.

Coach Dick Motta decided to move Dandridge to guard-a position he played briefly in Game 5-with th Bullets ahead, 87-82. San Antonio countered by covering Dandridge with Larry Kenon out front while Gervin, who normally plays against a guard, moved to defensive forward against Ballard.

It proved to be a poor tactical measure by Coach Doug Moe. Although Gervin made two shots down the stretch, he seemed reluctant to work against the pesky Dandridge, who bumped him and refused to let him waltz unmolested down he lane.

Once, Gervin drove the key but was cut off just inside the foul line by Dandridge. When the Ice Men went into the air, he decided to pass off. Dandridge blocked the pass, then was fouled at the other end.

That began a string at 10 Dandridge points in the final seven minutes, six coming after the Bullets had gone up by nine with four minutes left. Until then, he was only five of 21 from the floor, but once again proved unaffected by pressure at the end of games.

"I wanted to get my five best players on the floor at the same time," Motta said. "I was surprised that they put Kenon and Dandridge. In the Philly series, they put Gervin on Dr. J (Julius Erving) when he moved to guard."

Kenon, by far the Spurs' leading rebounder in this series, captured only one in the fourth quarter while stationed most of the time 20 feet from the basket. And Gervin just did not have the strength to handle Ballard, who is replacing injured Mitch Kupchak as the Bullets' number one sub.

Motta also pulled off a successful gamble when he began the fourth period with Unseld, who had five personal fouls by early in the third period before going to the bench. Unseld stayed to play the entire final guarter when the Bullets, out-rebounded by 10 for the night, commanded a 19-13 advantage off the iron.

The outcome of the game ultimately came down to Washington's ability to function under the intense atmosphere while San Antonio wilted, losing composure when the Bullet defense refused to give up prime shots.

We just didn't play well," said Moe, who also alleged the officials took away the game from his team.

"But it was my fault that Gervin was in so much in the second half. He was exhausted at the end. I should have rested him earlier and I didn't. Blame it on me."

San Antonio shot only 35 percent in the last quarter, during which Hayes blocked four shots and the Spurs went four minutes without a field goal.

Washington had began that period with a 54-49 lead, which later grew to 68-60 on a dunk rebound by rookie Dave Corzine, subbing for Unseld.

But the Bullets missed five straight shots, including three by Dandridge, who kept bouncing attempts around the rim, and San Antonio tied things on a fast-break layup by Coby Dietrick and went ahead 74-72 on a brea-away basket by Mike Gale.

Kevin Grevey responded with a couple of field goals off wide-open jumpers and Washington scratched out a 78-all tie going into the fourth period.

A three-point play by Hayes over Mike Green put Washington ahead for good, 85-82, and began a Keystone Kops performance by San Antonio tht included some shots shows.

Two foul shots by Ballard led to a Spur timeout and Motta could then move Dandridge to guard in place of the exhauted Grevey, who had been in for 15 straight minutes. He also replaced Larry Wright, who had eight of his 12 points in the first half with Tom Henderson, who finished with 11 points and eight assists.

Following another Gale failure, Hayes took a splendid pass from Dandridge and dunked it for an 89-82 lead. Gale responded with two free throws and Gervin added his first basket of the period around two Dandridge foul shots to narrow the margin to 91-86.

Ballard couln't sink an open 15-footer but Unseld pulled in the rebound and was hacked. He made two from the line and, after Ballard's successful rebound of a Dandridge miss, San Antonio again stopped the clock. Ballard now is shooting 71 percent for the series.

Kenon responded with his first basket of the quarter but Ballard once again got inside Gervin and put in a rebound.Hayes blocked a Kenon attempt and Dandridge sank two foul shots for a 101-90 advantage with 3:29 to go.

From then on, Washington could play out the clock. When it was finally over, Motta hugged Assistant Coach Bernie Bickerstaff in celebration of the upset.

"The series advantage was something we had given away," said Motta, "and we had to get it back. Now we have."

And now it's back to Capital Centre for a game that Motta already has predicted the Bullets won't lose.

"San Antonio knows that," he siad. CAPTION: Picture 1, Greg Ballard muscles between Billy Paultz and Mike Gale for two points. Ballard came off the bench to score 19 points - 10 of them in last quarter - in Bullet win. By Richard Darcey - The Washington Post; Picture 2, Bob Dandridge of Bullets flies toward the hoop to score. By Richard Darcey-The Washington Post