PHILADELPHIA – Kevin Garnett scored 27 points, grabbed 13 rebounds, and used a dominant second quarter to help the Boston Celtics beat the Philadelphia 76ers 107-91 on Wednesday and take a 2-1 lead in the Eastern Conference semifinals.

Whistled for a costly illegal pick late in a Game 2 loss, Garnett crushed the Sixers early and never let them think about a fourth-quarter rally.

Garnett scored 13 of Boston’s 32 points in the second quarter and the Celtics became the first team to win by double digits. Game 1 and Game 2 were each decided by one point.

Rajon Rondo had 23 points and 14 assists. Paul Pierce, playing with a banged-up knee, had 24 points and 12 rebounds.

Game 4 is Friday in Philadelphia.

“Our offense finally came alive,” Pierce said. “We moved the ball. We knew that’s what we were going to have to do to score 100 points.”

Garnett had somehow become forgotten in Boston’s offense in Game 2 until the fourth quarter.

Coach Doc Rivers said the Celtics simply weren’t going to the 16-year veteran because they had established an offensive presence in the low post.

The Celtics wouldn’t let that happen again.

They needed Garnett at his best in Philadelphia, where the Sixers had won their last four postseason games.

So much for that minor streak. Garnett yapped his way down the court after several big early buckets and clearly enjoyed taking it to the Sixers. He buried those 10 to 16 footers with ease in the second quarter to turn a seven-point deficit into a 13-point lead.

“I thought a lot of guys tonight came and they didn’t think about what they were not doing well,” Rivers said. “A lot of guys just came and played.