Robert Parish scored 27 points and grabbed 16 rebounds to lead a front-court assault that powered the Celtics to a 133-99 rout yesterday of Detroit in their Eastern Conference semifinal opener in Boston.

Boston bolted to an 11-point halftime lead. Detroit came no closer the rest of the way as the 34-point final margin was the largest lead of the game.

The best-of-seven series continues Tuesday in Boston.

Boston's centers and forwards -- Kevin McHale had 26 points, Larry Bird 21 and Cedric Maxwell 16 -- outscored Detroit's front line, 106-42.

"When Robert gets going like that and gets aggressive offensively, he really gives us a big lift," said McHale.

The Pistons were led by guard Isiah Thomas with 23 points and Vinnie Johnson with 20. But center Bill Laimbeer had only one point and three rebounds.

"We just played a horrendous game," said Laimbeer. "I played probably my worst game as a Detroit Piston."

Johnson's long jumper gave the Pistons their last lead, 43-42, with 7:29 left in the half. Boston outscored Detroit, 22-10, the rest of the period as the Pistons made just two field goals in the final 7:28.

Boston led, 64-53, at halftime and took control with a 20-6 run midway through the third quarter.

"We had a good one, a real good one," said Boston Coach K.C. Jones. "Detroit had a bad one. There's nothing complicated about that. There's no big stratergy."