CLEVELAND, March 24 (Ticker) -- LeBron James willed his team closer to its first playoff spot in eight years.

James scored 19 of his 36 points in the final period as the Cleveland Cavaliers overcame a horrid start for a 94-82 triumph against the Boston Celtics, who saw their postseason hopes take a serious hit.

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Cleveland (40-29) reduced its magic number to three for clinching its first postseason berth since 1998. It also increased its lead to 3 1/2 games over idle Washington (35-32) for fourth place in the Eastern Conference, which gets home-court advantage in the first round of the playoffs.

"Forty wins before the month of April feels good," Cleveland coach Mike Brown said. "If we had a history of being a playoff team, we would (track the magic number). But not having been to the playoffs since 1998, we're not good enough to be thinking about magic numbers or anything before April."

Boston held a 59-58 advantage going into the final period as Cleveland shot 40 percent (25-of-63) from the field through three quarters.

The Cavaliers shot 63 percent (12-of-19) in the final period, opening with an 11-4 burst. Marshall jump-started the charge with the first of his three 3-pointers in the quarter and James capped it with one of his own at the 8:03 mark, giving Cleveland a 69-63 advantage.

"We were really flat coming out," Brown said. "But we got mentally tougher as the game went along."

"It's a maturing process," Marshall said. "We're starting to put it together. We're closing out games."

The Celtics cut the deficit to a point on three occasions, the last time at 76-75 on a pair of free throws by Paul Pierce with 4:36 remaining.

Cleveland responded with a layup by Ronald Murray and a 3-pointer by Marshall, who scored 14 points.

Pierce made two more free throws, but James put away the game with a layup followed by a shot from the arc to make it 85-77 with 1:44 left.

"I wanted to try and put them away," said James, whose 19 fourth-quarter points were his best in any period this season. "If you let them hang around, they have some dangerous weapons, especially Paul Pierce. We wanted to stay aggressive in the fourth quarter."

"I thought, for whatever reason, our spirit was broken in the third and fourth quarters," Boston coach Doc Rivers said.

Pierce, who torched the Cavaliers for 50 points in a 113-109 double-overtime loss in Boston on February 15, scored 24 points on just 6-of-20 shooting.

"For the most part, we did get good shots," Pierce said. "I thought we moved the ball well. The ball just didn't bounce my way today."

Delonte Westcollected 14 points, seven rebounds and seven assists. Ryan Gomes collected nine points and 15 rebounds for the Celtics, who missed a chance to make up ground in the East.

Division winners last season, Boston (29-41) remained four games behind Philadelphia (32-36) for the eighth and final playoff spot in the East.