With a sloppy, lackluster performance, the Celtics simply didn’t take care of business

Miami’s Kyle Lowry (7) found the Celtics' Robert Williams blocking his path to the basket on a first quarter drive.Jim Davis/Globe Staff

A hoarse Ime Udoka couldn’t explain why his team revered back to its December form in the biggest game in several years in Boston. The Celtics needed a home win to reach their first NBA Finals in 12 years and the game was for the taking.

They should have understood by now the Miami Heat weren’t going to fold, they were going to respond with their best game of the series, which they did. The Celtics’ response was mostly inadequate for most of the night, and when they needed a few more big plays to seal the win, they folded in the final few minutes.

The main culprit was Jaylen Brown, who missed two free throws with 2 minutes, 18 seconds left that would have given the Celtics the lead, and Jimmy Butler continued his heroic night with a three-point play.

Butler and his teammates wanted it more Friday, they were not going to fade into the sunset and allow the Celtics to seize the glory. The Celtics needed that championship mettle and they played like frontrunners, a passive bunch until the fourth quarter.

And by then they needed to be perfect and they were far from that. Butler carried the Heat to 111-103 win with 47 points, 26 in the second half. He bested Jayson Tatum, who was again confused by Miami’s blitzing defense and never imposed his will on the game, and Brown, who followed his 21-point second half in Game 5 with 2 in Game 6, plus those two missed free throws.

The Heat played well, staved off every Celtics run with a pivotal shot and were the more physical team. The Celtics haven’t lost this series. There’s one more game, but they’re going to have to be better than they were in Game 6. They’re going to have to reach for something more than they have presented for this entire postseason, even that Game 7 win against the Milwaukee Bucks.

Maybe it was meant to be this way. The Celtics have never made things easy on themselves. They wasted two games in the Milwaukee series. They were plagued by a porous third quarter of Game 1 of this series. They played terribly in the first half of Game 3.

Yet, they’re here, one win from the NBA Finals, one loss from a crushing end to the season.

The Heat played the best they would possibly play. They hit shots they missed the previous five games. Kyle Lowry sipped some of his Toronto juice and produced several big moments with 18 points and 10 assists. The Heat made the big plays.

The Celtics? Well, Tatum had one shot attempt in the fourth quarter and four turnovers. Brown also had just one shot. Marcus Smart played his worst game of the series, chucking threes with the shot clock rolling down or just looking a step slow on his bad ankle. Al Horford made one shot in 33 minutes.

The Sloppy Celtics returned again, committing 18 turnovers, including 11 from Tatum and Brown.

“Yeah, it’s kind of indicative of how our nights have been in this series when we don’t take care of the ball,” Udoka said. “A lot of careless ones, unforced, and that got us behind. Obviously dig ourselves out of a hole from the get-go, got it back to 29-22 but weren’t playing our best at all. And throughout the game any time we got within striking range, it felt like we had a poor decision, whether it was a turnover and they got out and scored. So kept it at 5- to 7-point margin. So had chances and didn’t take advantage of them.”

The Celtics couldn’t really explain their lackadaisical start. They were complimentary of the Heat for their shot-making. They had no answer for Butler and made few adjustments in the second half, but by then it was too late, he was knocking down threes and attacking the rim. Before Friday, he had not made more than three 3-pointers in game in more than a year.

He brought his best Friday. Tatum and Brown didn’t and perhaps couldn’t.

“Two things: they attacked the basket, got to the free throw line,” Udoka said. “We had some poor fouls at timely possessions in the game, and they made timely threes, specifically late in the shot clock. We didn’t contest or get out on shooters as well as we should have, and so throughout the game we had our chances.

“We got off to a slow start. Butler was aggressive. We didn’t match his intensity. But every time we got within striking distance, got it to tie game, two, three points, got some costly turnovers, that they go down on and score on. It felt like we were playing behind most of the time due to that.”

The Celtics deserve criticism for their lack of intensity and execution at times during this game, but they were also playing a ticked off team that clearly heard Golden State’s Draymond Green predict the Celtics would win this series. The Heat were never going to be pushovers, as banged up and sometimes offensively challenged as they are. It’s going to take the best of Tatum and Brown to win Game 7. They are capable and they have given themselves little option to be anything but great or they will regret another missed opportunity for the ultimate prize.

“They responded to every time we made a run, every time we got close, every time we went up,” Brown said. “It’s almost like you can’t leave — in a game like this, and they got it going, can’t leave room for error, and we did, I did, we as a team did, and next game if we come out like that, we’ve got to be almost — we’ve got to be better. That’s what it came down to. They played an amazing game. They made crazy shots. But we’ve got to play great defense again and force them to make some of those shots again.”