BOSTON — The Boston Celtics are back in the playoffs. They want to be playing their best when those games start.

They were very good Wednesday night.

Paul Pierce scored 27 points, Kevin Garnett added 20 and Rajon Rondo had a triple-double as Boston clinched a postseason berth with a 113-99 victory against the Denver Nuggets.

It was the Celtics’ fifth win in six games and began a six-game stretch at home, where they’re just 22-12, worse than their 24-13 road record.

“We’ve been able to get the job done on the road but this is where we eat. This is where we set our table,” Pierce said. “Hopefully, we can just start playing well in this building and gather some momentum going into the playoffs.”

Pierce, who missed 10 games with knee, foot and thumb problems, and Garnett, sidelined for 10 games with a hyperextended right knee, have been healthy for a while. Pierce scored just five points Feb. 21 in a 114-105 loss in Denver while playing with a sore thumb.

“The Paul Pierce you saw out in Denver wasn’t the Paul Pierce that usually shows up to play,” he said. “Right now I’m as healthy as I’ve been all year and this is our time to start playing well.”

The Celtics remained tied with Atlanta for third place in the Eastern Conference.

“I’m just really focused on getting to the middle of April and being at our best” for the playoffs, Boston Coach Doc Rivers said.

The Celtics dominated inside and the Nuggets, one day after losing to the Knicks in New York, slipped a half-game behind the Dallas Mavericks and into a third-place tie with Utah in the Western Conference with their third consecutive loss.

Boston led by 21 points twice in the third quarter before Denver cut the lead to 87-80 going into the fourth. But the Celtics stayed ahead by seven to 16 the rest of the way.

Rondo had 11 points, 15 assists and 11 rebounds.

Carmelo Anthony had 32 points and J.R. Smith added 21 for Denver.

The Celtics played aggressively from the start, beginning with Garnett’s dunk on an alley-oop pass from Kendrick Perkins for the first basket. Capitalizing on the absence of defensive star Kenyon Martin, who missed his 11th consecutive game with left knee tendinitis, Boston scored 58 points in the paint.

The Celtics’ strong inside presence and attacking style were two positive signs. The win was their fourth straight at home, where they began a season-long six-game homestand in 12 days, culminating with a Sunday afternoon meeting with the Cleveland Cavaliers on April 4.

“Whether it’s home or away, I think it’s time to get momentum,” Rondo said.

Boston has reached the playoffs in all three seasons since Garnett and Ray Allen joined Pierce to form the Big Three. It won its 17th NBA title in 2008 and was eliminated in the Eastern Conference semifinals by the Orlando Magic in 2009.

The Celtics led 30-27 after the first quarter in which Pierce outscored Anthony, 14-11. It was 61-51 at halftime.