The Boston Celtics stepped up their run to the National Basketball Association playoffs on Tuesday by upsetting Miami 115-107 for their second victory over the Heat in 10 days.

Kevin Garnett recorded 24 points and nine rebounds and Rajon Rondo had 18 points and 15 assists for the Celtics (33-24), who are two games out of third spot in the Eastern Conference.

Boston has reached the NBA finals in two of the last four seasons but with an aging roster, few considered it a legitimate title contender until its recent run.

"We've been put to the back burner all year long, this is our opportunity to show the world we still have a lot left in the tank," forward Paul Pierce told reporters after scoring a team-high 27 points.

"It's a fun time of the year, the playoffs are right around the corner and we thrive in these situations."

LeBron James tallied 36 points, seven rebounds and seven assists for Miami, while Dwyane Wade scored 20, but the Heat (40-16) slipped three games behind top seed Chicago after suffering their second home loss in three games.

The Bulls beat the New York Knicks 98-86 in a late game in Chicago.

Miami had previously enjoyed a 17-game winning streak on their home floor.

Elsewhere in the NBA, it was: Cavaliers 103, Bobcats 90; Wizards 93, Magic 85; 76ers 107, Nets 88; and Mavericks 110, Kings 100.

In Miami, the Heat, dominated by the Celtics in a 19-point loss last week, fell behind by 11 after the first quarter and never recovered.

Boston stretched the lead to 18 at one point in the second before the home team battled to pull within eight by halftime.

Miami tried to make a final push in the fourth quarter where it cut the deficit to 108-103 with 2:21 remaining but the Celtics answered to make the game safe.

Boston shot 60 percent from the field and Rondo had his 18th consecutive game with double-digit assists, the longest such streak since John Stockton strung 29 games together in 1992.

The Heat have been inconsistent recently, with five losses in 10 games, and are looking to find form for the postseason.

"We're not at a period of concern. The team played well," Wade said. "They (Celtics) shot the ball very well. When they shoot like that, it's going to be tough to beat them."

In Chicago, Richard Hamilton scored 20 points and Luol Deng added 19 for Chicago. Hamilton had 18 points in the third quarter to help Chicago stay ahead after building a 12-point halftime lead.

Carmelo Anthony led the Knicks with 29 points.