The Celtics improved to 27-2 - the best start for a two-loss team in NBA history. And the 19-game winning streak broke the Celtics record set by the original Big Three in 1981-82.
Louis Williams had 16 points and eight assists, and Samuel Dalembert scored eight points with 13 boards for the Sixers.
The "Beat L.A!" chant became popular in the '80s when Larry Bird, Robert Parish and Kevin McHale seemed to play the Lakers for the title every year. It made a comeback last spring when the Celtics eliminated Los Angeles in six games to win their unprecedented 17th title.
Now the Lakers stand in the way of another bit of NBA history: A 20th win in a row would move the Celtics past Los Angeles' 1999-00 team and into a tie for the third-longest winning streak in league history. The 1971-72 Lakers won 33 in a row, the NBA record.
The Celtics led by 14 at the half and 22, 74-52, with 4:32 left in the third before the Sixers ran off 10 points in a row. But Powe pitched in with nine of the first 11 points in the fourth quarter, and the Celtics took a 95-74 on House's jumper with 6:17 to go.
House hit three 3-pointers in the fourth quarter, one of them a meaningless jumper at the buzzer.
The Sixers went 0-for-11 from 3-point range and are 0-for-19 in the last two games.
Notes: New England Patriots linebacker Junior Seau watched the game from courtside. ... Celtics F Glen "Big Baby" Davis, who was injured in a car accident on his way to Sunday's game, missed his second straight game and watched from the bench in street clothes. ... Tony DiLeo fell to 3-2 since taking over from Maurice Cheeks as Sixers coach. He also picked up his first technical foul.