BOSTON - From the beginning of this playoff run, which surprisingly reached a second round after a defeat of the top-seeded Chicago Bulls in six games, 76ers coach Doug Collins has talked of the importance of his young team seeing the ball go into the basket early and often.

That is exactly what happened on Saturday in Game 1 against the Boston Celtics as the Sixers, who averaged 22 points in the first quarter against the Bulls, dumped 28 on the Celtics and opened up leads as big as 13 in the first half.

After the Chicago series, Collins also talked glowingly about the Celtics' top-ranked defense and how hard it would be for his team to score at crucial times.

The Celtics' defense won out over the Sixers' offense Saturday as Boston pinned a 92-91 loss on the Sixers to grab the first game of the series.

"Defense," Celtics guard Rajon Rondo said when asked why Boston won the game. "We kept believing in ourselves."

While the shots fell for the Sixers in the first half, it was also easy to see what their defensive scheme seemed to be for the series - double team Paul Pierce as much as possible and live with the likes of Brandon Bass, Avery Bradley, and Rondo throwing up jump shots.

Like the offense, that worked well early as Pierce scored just two points in the first half, and those three Celtics combined to go 4 for 17.

That helped the Sixers blow out to a lead of 45-32 with 3 minutes, 44 seconds left in the first half.

That's when the Celtics appeared to get their late wake-up call. Over the next 10 minutes of the game, they used a 21-4 run to grab a 51-49 lead midway through the third quarter.

The Sixers, however, responded with an 8-0 run of their own later in the quarter and still led going into the fourth by 71-67.

For much of the third quarter, Collins put Lavoy Allen and Spencer Hawes on the floor together, a pairing rarely seen thus far. But it worked in clogging the middle, where the Celtics had been driving the ball earlier in the quarter. It was also done out of necessity as Thaddeus Young, who sprained his right ankle in the first half, didn't get off the bench.

He did return in the fourth quarter, but it was Allen's play that overshadowed anything else. The Temple product didn't see a minute of action in the Chicago clincher. But Saturday he came off the bench to score 12 points and grab six rebounds.

The turning point of the game came with fewer than three minutes remaining when Lou Williams missed a contested fastbreak layup with the Sixers leading by 84-83. The Celtics then got out on the run, and Rondo (13 points, 17 assists, 12 rebounds) fed Kevin Garnett (29 points, 11 rebounds) for a layup and he was fouled by Hawes. The free throw gave the Celtics an 86-84 lead with 2:52 left in the game. After a turnover by Williams, Garnett drained a long jumper, and Boston was on its way to a one-game-to-none series lead.

Andre Iguodala, the star on Friday after his two foul shots with 2.2 seconds remaining gave the Sixers the Chicago series, aggressively attacked Pierce on the offensive end all night and finished with 19 points. Pierce, who is hobbled by sprained ligaments in his left knee has admitted to having problems with his lateral movement. It was obvious from the beginning that he wasn't going to be able to deal with Iguodala's quickness.

Evan Turner scored 16 and grabbed 10 rebounds for the Sixers, while Hawes had 15 and eight. The Sixers turned the ball over only 11 times, but many came at critical moments that led to Boston baskets. That is a big area of concern for Collins.

"This is a team that averages about nine steals a game, so we have to take care of the ball," he said before the game. "The last series we concentrated so much on Chicago's offensive rebounding. In this series you have to take care of the ball. You cannot make high-risk plays against this team, because that is where they get easy scores."

Contact Bob Cooney at cooneyb@phillynews.com.