BOSTON — Kevin Garnett had 15 points and nine rebounds and the Boston Celtics played Miami-style defense to beat the Heat 85-76 in the opener of their playoff series tonight.

Trailing 44-41 at halftime, the Celtics held the Heat to 32 points in the second half. And with substitute guard Tony Allen shadowing Dwyane Wade, the Heat star scored 26 points after averaging 33.7 in three regular-season games against Boston.

Allen also scored a career playoff high 14 points, and Paul Pierce led Boston with 16. Quentin Richardson added 15 for Miami.

Game 2 is Tuesday night in Boston.

With 40 seconds left in the game, a scuffle near the Miami bench resulted in two technical fouls against Garnett, an automatic ejection, and one each to Boston's Glen Davis and Miami's Udonis Haslem and Richardson.

Miami allowed the second fewest points in the regular season, an average of 94.2, but was outscored 21-10 in the fourth quarter.

And Garnett had a big game after missing last year's playoffs because of a knee injury that required offseason surgery. Saturday's playoff game was his first since Game 6 of the 2008 NBA finals, a 131-92 win over the Los Angeles Lakers for Boston's 17th NBA championship. In that finale, he had 26 points, 14 rebounds, four assists, three steals, a block and no turnovers.

This year, both teams stressed that the playoffs were a new season and what happened before didn't matter.

They were right.

Boston won despite going 3-7 in its last 10 games. Miami lost after going 12-1 in its final 13 games and 8-0 in its last eight games on the road.

Trailing by two starting the final quarter, the Celtics tied the game at 68 on two free throws by Rajon Rondo, who had 10 points and 10 assists.

Then the 289-pound Davis gave Boston the lead for good with an acrobatic layup followed by a backwards somersault after he hit the floor when fouled by Jermaine O'Neal. Davis hit one of two shots.

Miami followed with a 24-second violation before a tip-in by Davis gave Boston a 73-68 lead. The Heat then missed their next two shots and Rasheed Wallace stretched the lead to six with one free throw.

Wade followed with a free throw, but Allen increased the lead to 76-69 with a layup. Michael Beasley hit a shot for the Heat but any chance they had faded as the Celtics scored the next five points on a dunk by Garnett, a free throw by Davis and a layup by Rondo.

In the first half, the Heat dominated the boards 23-15 and stifled the Celtics on defense to take a 44-41 lead at intermission. Miami ended the first quarter with a 29-28 edge, then Boston missed 10 of its first 12 shots in the second. But the Celtics rallied at the end, scoring the last five points of the period, the final two on a 13-foot jumper by Rondo at the buzzer.

Boston also used a late surge to cut Miami's biggest margin of the game, 14 points, in the third quarter. After Wade's layup made it 61-47 with 7:02 left in the period, the Celtics outscored the Heat 17-5 the rest of the way and trailed by just 66-64 going into the fourth. Pierce had the last seven points in the comeback and missed a 3-pointer as the buzzer sounded.