When things got tough, this Celtics team got tough — and they finally proved they belong with the elite

MIAMI — These are not the same ol’ Celtics.

They have finally overcome their past demons, past Game 7 horrors, past insecurities and lack of confidence that they weren’t good enough to beat the elite teams in the Eastern Conference.

They are the elite team in the Eastern Conference.

After a disheartening Game 6 loss, the Celtics punched first in Game 7 Sunday night at FTX Arena, led the Heat the entire way and then barely clung to their lead in the final minutes. But they made enough plays, got out of their own way and carried enough guile to prevail.

The 100-96 win thrusts the Celtics back to the NBA Finals for the first time in 12 years, where they will face the Golden State Warriors beginning Thursday in San Francisco.

How did they do it? After playing such a poor Game 6 in Boston, handing the Heat all the momentum? They reverted back to themselves, playing strong defense, moving the ball and reducing mistakes. They led by as many as 17 points, and then watched in total fear as Jimmy Butler pulled up for a potential go-ahead 3-pointer with 16.6 seconds left.

Perhaps the ball goes in two years ago or four years ago, but it rimmed out. Marcus Smart, whose hyper play and lack of poise at times caused them to nearly blow a 13-point lead, sank two free throws 11.4 seconds left to seal it. It was apropos.

The Celtics are 6-0 in the playoffs after losses and won three times in Miami in this series. They have become road warriors, playing their absolute best when the odds are the greatest.

“But that’s us. We’ve been responding all year, all season to adversity,” guard Jaylen Brown said. “Today was the biggest test, not just of the year but of our careers, to mentally come into a Game 7 away after losing on our home court, which was tough, and we got it done.”

The Celtics showed their best and worst in a four-minute span, they won Game 7 despite themselves. They have proved all series they were the better team, only beset by their own ineptitude and mistakes. They played mostly a brilliant Game 7, save for a litany of fouls in the second quarter.

Celtics center Al Horford (42) attacks the basket for a critical fourth-quarter basket and, fittingly, came up with the last defensive rebound of the game to send Boston to the NBA Finals.Matthew J Lee/Globe staff

They relied on teamwork, the energy of 36-year-old Al Horford and the clutch shot making of Larry Bird Trophy winner Jayson Tatum, who drained two critical shots to extend the lead and finished with 26 points, 10 rebounds, 6 assists and 2 blocked shots in a masterpiece all-around performance.

Tatum has clamored for stardom, clamored for respect and clamored for an opportunity to showcase his skills on the biggest stage. Game 7 was the biggest stage so far in his career and he responded, not by trying to shoot the Celtics to the Finals but using his array of skills to impact the game.

Tatum has been through his share of disappointments at age 24. He lost to LeBron James and the Cavaliers in 2018, experienced the Kyrie Irving-led meltdown in 2019 and was part of the breakdown during the Eastern finals two years ago against the Heat.

Tatum had to assert himself this season, take over games when the Celtics desperately needed it, serve as a leader on and off the floor. He was unusually gaudy after Game 6, saying his confidence level was at “10″ to win this series. He backed up his words. He was the best player on the floor Sunday — when it counted.

“I think in those moments, you don’t want to leave and feel like you could have done something more, so I think — I came in with the mindset today that I was willing to do anything it took to win this game, however that looked,” Tatum said. “We all talked about it. But I know especially for me, I came into the game, the only thing that mattered was winning.

“Y’all weren’t going to talk about how many points or how many shots I missed if we lost. It was all about, did you get it done or not? I knew that coming in today and the group knew that. I think coming in here and getting it done was big.”

Celtics guard Jaylen Brown (7) scored 24 points on 8 for 15 shooting to go along with 6 rebounds and 6 assists in a decisive Game 7 victory over the Miami Heat in the NBA Eastern Conference Finals.Matthew J Lee/Globe staff

Game 7 was a coronation of a talented team under a first-year coach that transformed into a juggernaut over several painful weeks, dozens of painful moments. They could have easily run away with Game 6, made their home fans happy, saved everybody a third trip to Miami in a week but that’s not their style. They spent the year challenging themselves, and they have met every challenge to date.

“Really the process. Really everybody, Coach Udoka was very clear what he wanted us to be as a team, our identity, defensively, hang our hat on the defensive end,” said forward Al Horford, reaching his first Finals in 16 years. “And on offense, play freely, use Jaylen and Jayson and just kind of just go. And us understanding and buying into that. It took us awhile, but I feel like once we started to understand how we needed to play, we became more consistent.

“This journey is not easy. We had a hard path. Brooklyn, Milwaukee, the defending champs, and Miami it’s a team that look what they did, they took us to the brink. For our group it’s resiliency, it’s switching the page, moving on to the next thing, and we did that all season, and I really noticed it, and I was telling this to JB, but it was like February, early February, that I just noticed how we started to click.”

You can criticize the Celtics’ late-game execution and decision making for sure, but the days are over where their toughness should be questioned. They were punked two years ago against the Heat in the NBA Bubble. They only wanted to win playing pretty basketball when gritty was required.

But Udoka changed the culture of the franchise, coached them hard, stunned them with his brutal honesty and allowed his approach to slowly digest, and it has. The Celtics were the tougher team in this series, and that’s perhaps the most flattering compliment of them all.

The Celtics took the hard route, but they reaped their just reward by hosting the Bob Cousy Trophy after winning the NBA Eastern Conference Finals in seven games.Matthew J Lee/Globe staff

When things got tough, this Celtics team got tough — and they finally proved they belong with the elite

Read more Celtics stories