Dwyane Wade scored 34 points, and LeBron James put the Heat up for good with a 3-pointer with 2:10 left on the way to a 33-point effort.

James added a series sealing 3-pointer with 40.4 seconds left.

A steal and two-handed slam 6 seconds later for good measure, followed by a Celtics turnover, got the party started. It was over, the Heat and Celtics knew it, and Boston coach Doc Rivers stood silently near the bench, his arms folded across his chest as James ran down the clock on Miami's final offensive possession of the series.

Boston was thoroughly worn down by a younger, more athletic opponent. The Celtics won the first three meetings between the clubs this season, then lost five of the final six.

Miami took another step on delivering on the massive pre-season investment that attracted James and Chris Bosh to join Wade in an intimidating lineup.

Next up will be either Chicago or Atlanta, in a series that may start as early as Sunday. Chicago leads the series 3-2.

"It's a great team," James said of the Celtics. "I got the utmost respect for that team. They're the reason why all three of us came together, is because of what they did, that blueprint they had in '08 when they all came together." Bosh finished with 14 points and 11 rebounds, including head-faking his way past Kevin Garnett for a game-tying dunk with 2:57 left.

The rest was up to James. He scored the game's final 10 points, putting to rest talk that he couldn't be effective late in games.

"I never even got to all that with (what) everybody was saying about me in late-game situations," James said. "I know what I work hard for, and that's to be put in those positions. My coaching staff gave me a lot of confidence.

Teammates kept giving me confidence, and happy to bring it home." It's Miami's fourth trip to the East finals, its first since 2006.

Ray Allen led Boston with 18 points. Garnett had 15 points and 11 rebounds, Paul Pierce scored 12 and Delonte West added 10.

Rajon Rondo finished with six points in 31 minutes for Boston, playing in a brace over the elbow he dislocated during Game 3.

Boston led virtually all of the first three quarters - Miami led for only 1:45 of the game's first 36 minutes - but that hardly meant the Celtics were in control. Boston's lead was only 73-71 entering the fourth.

And when everyone went cold to open the fourth, Boston seized a bit of control. West scored six of the Celtics' first eight points in the final quarter, the last of those coming on a drive with 9:21 left for an 81-74 lead.

In Oklahoma City, the hosts blitzed Memphis to take their first lead in this series, three games to two.

Kevin Durant scored 19 points and reserve Daequan Cook added 18 for the Thunder, who won comfortably after the triple-overtime effort in the previous game.

Marc Gasol had 16 points to lead Memphis, which matched its lowest point total from the regular season and played like it was still drained from the emotional overtime loss.

The Grizzlies shot a season-worst 36 percent and were far enough behind that Durant and Thunder teammate Russell Westbrook were rested in the fourth quarter.

"We played great defense. Everyone was in tune, locked in," Durant said. "It was a group effort." Memphis' Zach Randolph, who played 56 minutes in the marathon Game 4, never was effective. He finished with just nine points and seven rebounds, and even missed four of his first five free throws.

Gasol did most of his damage during a 6-minute stretch in the third quarter. Then the Grizzlies fell hopelessly behind.

Oklahoma City's Nick Collison turned a rebound into a three-point play. When he converted the free throw, it completed a string of seven straight points by the Thunder to bump the lead to 65-46 late in the third quarter.

Memphis didn't stand a chance of a comeback. Too many missed layups. Too many short shots that clanked off the front rim. Too little energy left.

Mike Conley made just 4 of 16 shots, Tony Allen was 4 for 13 and O.J. Mayo 2 for 8 on a dreadful night when nothing was going in.

"It wasn't a factor at all. We wouldn't let that beat us," Durant said when asked about fatigue. "We came out ready." Memphis didn't reach 50 points until there was 2:04 left in the third quarter, and the Thunder quickly squelched any hopes of yet another wild comeback after the Grizzlies had overcome double-digit deficits to force overtimes in each of the previous two games.

Collison had a two-handed dunk, Cook hit a 3-pointer and Nazr Mohammed made a layup during a string of seven straight Oklahoma City points early in the fourth quarter and the lead grew to 27 before both coaches emptied their benches for the final 4 minutes.

"We're going to need them and they know that," Durant said of the reserves, who got more than the usual minutes.

Westbrook had 11 points in 25 minutes - half of what he played in Game 4. Mohammed added 10 points and Collison had nine points and 10 rebounds, helping the Thunder to a 50-33 edge on the boards.