John Williamson sent the game into overtime with a short jump shot with two seconds remaining in regulation today, then scored seven points in a 43-second span of overtime as the Washington Bullets shocked the Boston Celtics, 133-128.

The victory, coupled with Philadelphia's triumph over San Antonio, vaulted the Bullets past the Spurs into sixth place in the Eastern Conference. If they stay there, they will be assured of a spot in the playoffs for the 12th straight season.

With Elvin Hayes scoring 35 points and adding 17 rebounds, the Bullets recorded their eighth victory in their last 10 games, ending a nine-game Celtic winning streak. They also became the only team to beat Boston at home twice this season. They won here, 118-105, on Jan. 25.

The Celtics had won 19 of their last 22 games and they are probably the deepest team in the NBA. Today, they came at the Bullets in waves and never seemed to let up.

The Bullets tried to control the tempo and stay calm.

They did, even when they were down by 14 points in the third quarter.

The Celtic bench has the big names: Dave Cowens, Pete Maravich and M. L. Carr. But Bullet reserves Williamson, Larry Wright and Lawrence Boston stole the show today.

Wright scored 16 points and had five assists while playing 19 minutes -- all in the second half.

Boston in the game for Wes Unseld, who played 43 straight minutes before fouling out, scored seven points and had eight rebounds.

Williamson made the biggest difference of all.

"I had to prove something to myself today," Williamson said. "I had to make up for what I had done the last two games."

Williamson made one of 12 shots against the New Jersey Nets Thursday and followed that with only five points Friday against the Pistons, afterwards saying that he just didn't feel like playing.

The same could not be said today. His running one-handers were going in today and he exuded confidence.

The Celtics had a 115-108 lead with 1:33 left in regulation and the Bullets looked dead. But Wright, Greg Ballard, Williamson and Boston wouldn't let them die.

Boston was fouled battling Rick Robey for a rebound and made one free throw to cut the lead to 115-109.

Boston stole a pass intended for Larry Bird and Wright got a fast break layup to cut the lead to four points with 39 seconds remaining.

Ballard knocked the ball away from Gerald Henderson on the Celtics' next possession and Henderson fouled Wright.

The Bullet guard converted two free throws with 28 seconds to play and the Bullets were down, 115-113.

Bird, who finished with 33 points, missed a difficult shot over Ballard with six seconds to play and Hayes rebounded it and called timeout.

The Bullets set up a play designed to run Williamson through three picks for a shot along the baseline. It worked perfectly. He got Dave Corzine's midcourt inbounds pass 12 feet from the basket along the left baseline, took one dribble and tossed in a soft eight-foot jumper with two seconds to go to send the game into overtime.

A turnaround jumper by Hayes, a three-point play by Ballard and a driving dunk by Wright started the Bullets off quickly in the overtime period. But the Celtics, who still have the best record in the NBA at 53-16, clawed back.

A three-point play by Chris Ford and two free throws by Tiny Archibald tied the score at 124 with 4:36 left.

It was "Supe Time." He made one of his special fade-away jumpers as he was being fouled by Ford. He converted the three point play for a 127-124 Bullet lead.

Archibald got the Celtics back to within one with two free throws with 1:03 left.

Williamson took the inbounds pass and controlled the ball for 23 seconds before throwing in a running one-hander from 18-feet to give the Bullets a 129-126 lead.

Archibald tried to hurry the ball up court for the Celtics, but Williamson snuck a hand in and knocked the ball away to Ballard, who fed Williamson for a breakaway layup with 32 seconds left.

That put the Bullets ahead, 131-126, and the capacity Boston Garden crowd of 15,320 finally gave up.

"I've always taken the pressure shots," Williamson said. "I like it that way. I wanted to play real bad today. I know I had let my teammates down with two bad games in a row, and I didn't like the way that felt."

The Bullets will have only one day to savor the victory. They have another very important game Tuesday at Capital Centre against the Spurs.