"The difference (tonight) was we played with a lot of energy," said Pierce, who scored just three points in the first half after getting in early foul trouble. "Our defense was there from the start, regardless of when we were in foul trouble. The energy was just there and we can play with anybody regardless.
"If we play with type of intensity, we rebound the ball and we get out on the break, we are going to be tough to beat."
Antoine Walker added 17 points and Walter McCarty and Tony Delk had 14 apiece for Boston, which held Indiana without a field goal for an incredible 14:19 bridging the final two quarters. The Celtics shot 45 percent and limited the Pacers to 33 percent. Indiana made just two of 15 shots in the third period.
"I never thought that we would shoot the ball this poorly," Pacers Coach Isiah Thomas said. "They had good looks and we just didn't knock shots down."
Indiana drew within eight points with 6:28 remaining in the third quarter when Ron Mercer made a jump shot. But the Pacers did not make another field goal until Erick Strickland hit a jumper with 4:09 left in the contest.
"We played an inspired game of basketball and it's going to take those types of efforts to get a team like Indiana out of the playoffs," Celtics Coach Jim O'Brien said. "We played both ends of the court and we played it for four quarters. And I was very pleased with what we put out there tonight."
"Coming out of (halftime), Walter did a tremendous job on (Jermaine) O'Neal and then Paul came back and got the rebounds, and that is what we ned as the series goes along," Walker said.
The physical game saw one player ejected from each team. Boston center Mark Blount was tossed after a hard foul on O'Neal with 10:41 left in the second quarter while temperamental Pacers forward Ron Artest was ejected after picking up his second technical following a foul on Pierce with 2:40 to play.
The Pacers were whistled for five technical fouls and the Celtics were called for two flagrant fouls.
"I thought they were pretty aggressive and pretty physical at the start of the game in terms of the hard fouls that they were giving, and I thought our guys did a good job in just maintaining their composure and not playing into it," Thomas said.
"We are trying to be the aggressor in this series," Walker said. "They were known throughout the season as being very physical and we are trying to rise to the challenge and be just as physical as they are and play smart and not get caught up in the refereeing and how the game is going to be called."
O'Neal contributed 21 points and 16 rebounds to lead Indiana. Artest added 20, but hit just six of 18 shots.
Reggie Miller scored only five points and was held without a field goal for the first time in his stellar 112-game playoff career.
"First of all, personally, it's tough," Miller said. "You come in with such high expectations. Obviously we have to win one here to re-capture home court advantage, and to have that type of shooting game I had is very tough. I think collectively as a team we're going to have to match their energy."
Walker and Eric Williams scored 10 points apiece in the first quarter to stake Boston to a 31-15 lead. Walker capped the period with a three-pointer at the buzzer.
After Blount's flagrant-2 foul, the Pacers went on a 26-10 run and took their first lead, 42-41, on a baseline jumper by Artest with 1:33 left before halftime. Tony Delk gave Boston the lead for good, 45-44, on a jumper with 31 seconds left, then closed the scoring with three free throws after Tim Hardaway committed an ill-advised foul with two-tenths of a second left.
Boston improved to 19-2 this season when scoring at least 100 points.
Game 4 will be Sunday at Boston, where the sixth-seeded Celtics have won their last five games against the Pacers.
"If we get those same shots Sunday, I think we'll have a different story here," Thomas said.