MIAMI (NBA) - LeBron James finally got the better of the Boston Celtics, taking over down the stretch and helping the Miami Heat to a 97-87 win that wrapped up their Eastern Conference semi-final series 4-1.

Boston led for much of the way and went up 87-81 on a jumper by Nenad Krstic with 4:28 left to play.

But Miami responded in emphatic fashion, scoring the last 16 points of the game to send the defending Eastern Conference champions packing.

The Heat return to the conference finals for the first time since 2006 when they won their first-ever NBA championship.

James, who had seen his playoff runs with the Cleveland Cavaliers ended by these same Celtics in 2008 and 2010, scored the last 10 points on Wednesday to put the game beyond reach.

Following Krstic's basket, Dwyane Wade hit a pair of free-throws and sharp shooter James Jones buried a three-pointer.

Chris Bosh then drove past Kevin Garnett for a dunk that tied the score at 87 with 2:57 to play.

James singlehandedly closed out the game, hitting two three-pointers, a breakaway dunk and a basket inside.

Afterwards, he showed his emotions at overcoming the biggest obstacle in his career to date as he knelt on the court while his team-mates celebrated.

"Finally getting over this hump against this team. Everything I went through this summer with 'The Decision' and deciding to come here to be a part of this team," he reflected.

Miami's Big Three combined for 81 of their team's 97 points and hauled in 28 of their 38 total rebounds.

Meanwhile, the Oklahoma City Thunder had a comfortable 99-72 win over the Memphis Grizzlies to take a 3-2 lead in their Western Conference semi-final.

The Grizzlies looked to still be dealing with the fatigue of playing three overtimes in Monday's epic Game 4. They shot just 36 percent from the field and the 72 points was a season low.

“It’s always better for the home team in these situations, and the team that won the game,” said Grizzlies head coach Lionel Hollins.

“Not only were we physically down, we were probably down a little bit mentally, but I’m not making excuses for our group.

“We didn’t play very well. We didn’t shoot the ball very well. We missed a ton of layups.”

Kevin Durant had 19 points for the Thunder who pulled away in the second quarter and never looked back.

Spain international Marc Gasol had a team-high 15 points for Memphis but grabbed only five rebounds, while Zach Randolph was kept in check, contributing only nine points and seven boards, well below his series averages.

Gasol conceded that Memphis now have a huge task at hand.

“We’ve got our backs against the wall and we’ve got to bounce back and come out at home swinging,” he said. “We have no other chance to lose another one.

“We’ve got to go right away and win the next game. There’s no other choice.”

On Thursday, the Chicago Bulls look to close out their semi-final series against the Atlanta Hawks.

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