The Rockets hadn't lost since a 97-89 defeat to Utah on Jan. 27 and put together the NBA's second-longest winning streak. It ended 11 victories shy of the 1971-72 Los Angeles Lakers, who won 33 in a row.
It was only Houston's second loss in 28 games and its fourth since a 97-93 loss in Boston on Jan. 2, a game Tracy McGrady sat out with a knee injury. The Rockets also lost for the first time in 11 games since Yao Ming went out with a season-ending foot injury on Feb. 26.
Luis Scola scored 15 for Houston, which had a 15-game home streak snapped. Only the 1985-86 Rockets, who won 20 straight at The Summit, had a longer home-court streak in franchise history. McGrady had eight assists and seven rebounds, but only eight points on 4-for-11 shooting.
Reserve Leon Powe added 21 points for the Celtics, who've won 13 of their last 14 games, the last three without All-Star guard Ray Allen, who's out with a sore left ankle.
The Rockets still have one more streak to protect -- they'll go for their 13th straight road win in New Orleans on Wednesday night. Houston beat the Lakers on Sunday to take over sole possession of first place in the Western Conference and set up Tuesday's showdown between conference leaders.
They were tied at 40 at halftime, but Boston took control in the third quarter, led by its All-Star duo.
Garnett swished a jumper from the top of the key 15 seconds out of the break and Pierce sank a 3-pointer on Boston's next trip down, the start of an 18-5 spurt. The Rockets missed eight of their first 10 shots out of the break and stopped getting the bounces that had always gone their way throughout the streak.
Even when Houston got aggressive, it backfired.
With 3:18 left in the third quarter, Tony Allen drove the baseline and McGrady and Scola both jumped to block him. McGrady blocked the ball, but Scola whacked hit Allen and sent him hard to the court. Referee Scott Foster called a flagrant foul on Scola as Allen lay on the floor for several minutes. He finally got up and hit two free throws to put Boston up 64-52.
McGrady missed a jumper in the final seconds of the third quarter and Battier was there for the rebound, but tipped it right to James Posey, who started a fast break the other way.
The Celtics outscored Houston 32-16 in the third quarter and built a 72-56 lead, the largest deficit the Rockets had faced since Boston had them down 20 in their first meeting. Houston went 7-for-16 from the field with six turnovers in the decisive quarter.
Boston pushed the lead over 20 early in the fourth quarter. During a timeout, the crowd stood and applauded as a video on the scoreboard finished with a shot of the arena and the line: "Where 22 in a row happens."
The rest of the game was a cold dose of reality.
McGrady left with 8:45 left and fans slowly filed out of the arena. With 2:09 left, Garnett drove down the line and hammered home a one-handed dunk, then added a milder throwdown on Boston's next possession.
The loss dropped Houston back into a first-place tie with the Lakers in the West. The Hornets are one game behind heading into Wednesday's matchup.
Notes: Boston coach Doc Rivers said he would re-evaluate Ray Allen's injury on Wednesday. Rivers said Allen could "possibly" play in Dallas on Thursday. ... The Celtics have won seven straight road games and all seven meetings against teams from the Southwest Division. ... Former Rockets center Hakeem Olajuwon had a courtside seat for the second straight game. ... Rockets rookie forward Carl Landry sat out for the sixth straight game with a bruised right knee. Landry will travel with the team to New Orleans for Wednesday's game.