After Kevin McHale missed two free throws that could have cost the Celtics the game with 39 seconds left in regulation yesterday, he said he closed his eyes and said a little prayer.

"I begged for another chance," he said. "I had visions that the bottom line of this game would say, 'McHale chokes, Celtics lose.' "

McHale got his second chance and rewrote the last line.

The 6-foot-11 second-year man scored Boston's first six points in the overtime period and made a key block on Kevin Grevey's three-point attempt that would have tied the game with 10 seconds to play. The Celtics went on to defeat the Bullets, 103-99, yesterday at Capital Centre to take a 3-1 lead in their best-of-seven playoff series. Boston can clinch with a victory at home Wednesday night.

"When I saw Grevey get the ball, I knew he was left-handed and that he leaped in when he shot," McHale said of his critical blocked shot. "He's no World Free, either, so he doesn't jump all that high on his shot. He also shoots it low off his shoulder. I didn't want to take a chance at fouling him, so I kept a couple of extra feet between me and him and made the block."

Many of the Celtics had an off day, including Larry Bird, who missed 12 of his 16 shots and did not have a field goal in the second half. So McHale, Robert Parish and Cedric Maxwell took over.

Parish had his second straight strong game with 28 points, 15 rebounds and three blocked shots before fouling out. McHale, playing all three front court positions during the game, totaled 25 points, seven rebounds and five blocked shots.

McHale and Parish scored 30 of the Celtics' final 53 points after the Bullets took a 60-50 lead with 7:38 left in the third period. For the game, Parish (11 for 19) and McHale (12 for 19) shot 61 percent. The rest of the Celtics shot 28 percent.

Bird missed all six of his second-half shots, including three straight in the overtime period.

"Maxwell was the first to realize that nothing Larry threw up was going in," said Boston Coach Bill Fitch. "So he started to go for the rebound before Larry even released the ball." Maxwell got 13 rebounds, five offensive and three of them off misses by Bird.

But this was a day when McHale once again showed his value to the Celtics. "To me," said Bullet forward Greg Ballard, "he's their most valuable player."

McHale got most of his points after offensive rebounds or from his soft, 12-foot turnaround jump shot.

"The main thing about him is that he can put the ball on the floor and go left or right, and that's a distinct advantage for a big man," said Rick Mahorn. "He's awkward, but he's flexible."

McHale said he knew he had the game in his hands when he went to the foul line with his team trailing, 90-89, with 39 seconds remaining. "I was nervous and I was thinking about everything but making the shots."

To McHale's relief, the game went into overtime, tied at 91.

McHale had two turnaround jumpers and a basket after an offensive rebound to tie the game at 97-97, accounting for Boston's first six points in the extra period.

The Celtics' lead was 100-97 after two free throws by Tiny Archibald with 18 seconds left. The Bullets called time out to set up a three-point shot. Kevin Grevey had one from the top of the key, but McHale blocked it cleanly to preserve the victory.

Fitch said his team is not playing badly and gave the Bullets credit for playing the NBA champions so well. "We're going at it as hard as we can," he said. "They just have a darn good basketball team."

McHale said this series has laid to rest the thought that the Celtics can't play halfcourt basketball. "We can't get our fast break going because they won't let us," he said. "I think they felt we couldn't beat them in a halfcourt game, but we've shown them we can." The Celtics scored nine points off the fast break Saturday and only eight yesterday. They also had 19 offensive rebounds that accounted for 20 of their points.

"The Bullets are pushing us to the limit," McHale said, "and we still have to win one more game against them. I know it isn't going to be easy because they aren't going to quit. I don't think they know how to. I have to be honest, though, I'm surprised at how good they are. They weren't this good a couple of months ago."