Even as the Philadelphia 76ers were using their fast break and muscle to take an early lead today in Game 3 of their Eastern Conference final series against the Boston Celtics, it seemed something wasn't right.

Sure, Andrew Toney, three of 17 from the field in Game 2, was scoring, but the points were on layups, not on his awkward corkscrew jump shot. And even though Charles Barkley was showing bravura, the Celtics didn't seemed overly concerned.

Perhaps that early coolness under fire was the main reason for the 105-94 victory that moved the defending champion Celtics to a commanding 3-0 lead over the 76ers in the best-of-seven series. The fourth and possibly deciding game will be played here Sunday at 1 p.m. (WDVM-TV-9, WBAL-TV-11).

Larry Bird led Boston with 26 points, and five other Celtics scored in double figures. Philadelphia was led by Toney's 26 but fell prey to self-destructive ways. Troubled by their lack of inside punch and outside scoring from Toney, the 76ers seemed intent upon solving both problems early. The result was a tendency to lapse into hesitant play, with no one besides Barkley willing to mix it up and try to take control.

Still, Philadelphia made things extremely uncomfortable for the Celtics in what was easily the most exciting game of the series. Part of the reason was that, according to Boston Coach K.C. Jones, "We weren't exactly the picture of perfection either. Our passing and shot selection weren't that great."

Ahead, 48-47, at halftime, Boston was unable to increase that lead beyond five points in the third quarter or beyond eight until the last two minutes of the game.

The game attracted 17,921, the first time this postseason that the 76ers have sold out the Spectrum.

Sunday's game could be the 76ers' last chance to match that achievement. Never has a team come from a 3-0 deficit to take a best-of-seven series, as Philadelphia Coach Billy Cunningham knows. "We have to find a way to motivate ourselves," he said. "We have to take one game at a time and get ready for tomorrow."

Today's game appeared to be Philadelphia's best opportunity. Despite their woes and the Celtics' overall control of the contest, the 76ers trailed by only 92-86 with 4:30 to play. Nine seconds later, Barkley scored on a layup to cut the margin to four, but Boston regained the points on Danny Ainge's two free throws.

On the 76ers' subsequent possession, however, Barkley was called for traveling. Bird made two more free throws to make the score 96-88 with 3:23 to play. Moses Malone got two points back from the foul line, but a short time later Philadelphia made another self-defeating play.

With the shot clock running out on Boston, Robert Parish took an off-balance shot. Ainge, the shortest Celtic on the floor, rebounded. Given another 24 seconds, Boston put the ball in the hands of Bird, who scored a swooping layup at the 2:34 mark to make the score 98-90 and effectively seal the victory.

"I think the credit should go to our defense," Dennis Johnson said. "We were able to pick their people up better in the second half. Then again, they had a lot of people standing around."

Perhaps the player hurt the most by the 76ers' strategy was Julius Erving. Increasingly removed as the team's focal point, today he scored five points, matching a career playoff low, and made one of 10 field goal attempts. He referred postgame questions on the team's play "to the coach."

But there wasn't much more that Cunningham could add. "They just got on a roll. When we had the opportunities we couldn't cash them in and they cashed theirs in all the time."

There was some disagreement as to why. "We really made all the big plays down the stretch," said Bird. "We were hitting the big shots and coming up with all the loose balls."

Erving, though, felt that his team "has been charitable through the whole series, like we've given them three games. I'm surprised that they're up 3-0, I bet they are, too."