Dwyane Wade (23 points, six rebounds, six assists) and the Miami Heat are headed back the NBA finals after outlasting the aged Celtics in Game 7 at home. (Mike Ehrmann/Getty Images)

The Miami Heat didn’t merely win a second straight trip to the NBA Finals Saturday night. The Heat staved off a burial. With its 101-88 victory over the Boston Celtics in the decisive Game 7 of the Eastern Conference Finals, Miami made its most vocal critics sit right down, thank you very much, for at least another week.

Instead of trying to figure out whether LeBron James, Dwyane Wade and Chris Bosh would ever play together in another game for Miami, the Heat will try to figure out how that trio can upend the Oklahoma City Thunder, which it will meet Tuesday in the Finals opener.

Once again facing the pressure of an elimination game that could have resulted in a dismantling of the franchise, the Heat looked cool and composed as it brushed off Boston late in the fourth quarter of a classic thriller.

Two nights after scoring 45 points in a huge blowout victory that kept the Celtics from the clinching the series on their home court, James roused the American Airlines Arena crowd by muscling in layups, slamming home dunks and hitting critical late field goals, one well beyond the three-point arc.

He led Miami with 32 points and 12 rebounds.

“It’s been a journey,” James said. “It’s been a long ride. . . . We didn’t shortcut anything this year. We said to each other, ‘It’s time. It’s time.’ ”

For the Celtics, the defeat brought sadness and a bit of nostalgia. It wasn’t just the end of a series, but also the end of a rich, celebrated era. There likely will not be another Finals opportunity for the NBA’s first big three, Kevin Garnett, Ray Allen and Paul Pierce. The trio, assembled in 2007, won one NBA title together in 2008.

“It’s probably the worst feeling that we feel in our lives, in our careers,” Allen said. “Now, there’s so much emotion. This one hit me hard. We wanted it so bad.”

But after hanging close with Miami for the first 41 minutes of the game, Boston couldn’t keep pace late. The Heat got 23 points from Wade, who tallied six rebounds and six assists. Bosh contributed 19 points on 8-of-10 shooting and eight rebounds; Shane Battier scored 12, all on three-point field goals.

Pierce led Boston with 19 points as Brandon Bass chipped in 16, Ray Allen, 15, and Garnett tallied 14. Rajon Rondo scored 22, grabbed 10 rebounds and handed out 14 assists.

“We had nothing left, that’s how it felt as a coach,” Celtics Coach Doc Rivers said. “Everything was front of the rim. We started throwing balls away. They started beating us off the dribble. . . . [It’s] frustrating as a coach. It felt like, ‘Let’s get away from them, let’s get away from them. We can’t let them hang around.’ And we did.”

Miami won the first two and final two games of this series as Boston won three in the middle. Two of the games went to overtime and only Game 6 was not close. James, who in last year’s six-game defeat in the Finals against the Dallas Mavericks largely disappeared in the fourth quarters, might have put a lasting stamp on his career with his otherworldly performance in the final two games. Tonight, he and the Heat stood tall in waning minutes; he scored 11 points in the final period.

“I try to lead by example and lead by my voice,” James said. “I can’t worry what people say about me, about my game, or who I am as a person. . . . For me, I just go out and play at a high level, do whatever it takes to win. I could be happy with that.”

With the score tied at 73 entering the fourth quarter, Miami and Boston engaged in a gripping offensive shootout. There were eight lead changes in the first five minutes of the final quarter. As Rondo, Garnett, Pierce and Allen scored for Boston, the Heat got flying dunks from Wade and James, and a cool layup in traffic, plus a foul, from James as Miami went up 83-82 with 7:34 to play.

“We just said, ‘Listen, we gotta keep playing, gotta keep playing, hopefully you’ll see them look a little tired,’ ” Wade said. “Tonight we made the plays. We made the shots to put us over the hump.”

Miami used a 15-4 run to take a 98-86 lead with 2:53 remaining. The rally started with a three-point shot from Bosh — his third of the night — and it included a long three by James, who finished the shot with a flourish, holding his right hand extended for several seconds.

Rivers called that shot a “backbreaker.”

James “played incredible,” Bosh said. “You have to credit all the times he just thinks about what happened last year; he just thinks about how he can improve. . . . He just has to believe in his ability and be himself. He doesn’t have to step outside of who he is because he’s the best basketball player in the world.”

Unlike Thursday night, Boston looked ready to play from the start. The Celtics jumped out to a nine-point lead in the first quarter as all five starters contributed as least four points. Miami, meantime, turned the ball over six times, resulting in eight Boston points, and entered the second quarter trailing 27-23.

Seven straight points from Bosh helped Miami tie the game early in the second quarter, but Boston took advantage of the Heat’s sloppy passing to stretch its lead to 11 and enter halftime up, 53-46. Miami, however, tied the game up early in the third and didn’t let Boston get away again.

And in the end, Boston ran out of gas. The Celtics scored just two points in the final three minutes.

“We had a great season, but we let this one slip away,” Rondo said. “We had some great looks . . . we just didn’t knock them down. . . . Give them credit . . . they played great tonight as a team and we just came up short.”