By Matthew Geagan, CBS Boston

BOSTON (CBS) — The Celtics had trouble winning any game to start the season, let alone securing a “signature” win. That changed Thursday night in Miami.

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The Celtics doused a bucket of cold water all over the Miami’s hot start to the season, handing the Heat just their second loss and the first on their home court. The Boston defense was an asbestos blanket draped all over the Heat offense throughout Thursday night’s game, holding the NBA’s best scoring team to a season-low 78 points and just 34.6 percent shooting.

Miami had won five straight games by 13 or more points heading into Thursday’s tilt, putting up at least 106 points in each of those wins. But the Celtics came in angry and took it out on the Heat, locking down Miami’s scorers while going ahead by as many as 26 points.

And unlike Monday night when the Celtics blew a 19-point lead to the Chicago Bulls, this lead would not be relinquished.

The Celtics kept up their defensive pressure and kept moving on offense for the entire game, and walked off the court with a 95-78 victory after their finest performance of the year. It was a full 48-minute effort, and the second quarter was easily their best 12 minutes of the season. The Boston defense forced 10 turnovers that frame and held Miami to just 3-for-13 shooting. The Celtics easily won the quarter, 33-9.

“That second quarter, we locked down there. Credit our guys,” said head coach Ime Udoka. “We switched up some coverages. We did a great job of limiting those guys. Defensively, that’s exactly what we want it to look like.”

Bam Adebayo was met with a wall whenever he entered the paint. Sharpshooters Duncan Robinson (5-for-17) and Tyler Herro (3-for-11, 0-for-4 from three) were never allowed to get into a rhythm. Jimmy Butler was held to just 20 points on 8-for-18 shooting.

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Miami committed 18 turnovers on the night, and the majority of them were forced by Boston’s unrelenting defense. The Celtics made it a point to muck things up on that end of the floor, poking loose any ball that the Heat made available.

Doing this on the second leg of a back-to-back is impressive. Making the victory all the more awe-inspiring is that Boston won with Jayson Tatum still struggling from the floor. He didn’t score until there were 11 minutes left in the game, and hit just three of his 13 attempts from the floor. Jaylen Brown led the way for the C’s with 17 points, but left in the fourth quarter with hamstring tightness. Tatum woke up after Brown’s departure, finishing with 10 points.

But they were just two of six players to log double figures in scoring for Boston. Al Horford continues take a swig from the fountain of youth before every game, and finished with 10 points, seven rebounds and a pair of blocks. The Celtics bench was a massive part of Thursday’s win, with Dennis Schroder (14 points, six assists, five rebounds), Romeo Langford (12 points) and Aaron Nesmith (13 points off 5-for-8 shooting) each coming up big off the pine.

It was Schroder and Langford who sparked an 11-1 run by Boston at the end of the third quarter, just when it looked like the Celtics were about to blow another second-half lead. Schroder swiped the ball from P.J. Tucker under the Heat basket and went coast-to-coast for a layup to put Boston back up by 10, and Langford canned a corner three off a Robinson miss to make it a 13-point Celtics advantage. Schroder closed the frame with a three-point play to give the Celtics an 18-point lead heading into the final quarter.

The Celtics bench scored 45 points on Thursday night, accounting for 47 percent of Boston’s offense. Add that to the team’s stout defense throughout, and the Celtics turned in their best win of the young season.

Boston has now held their last two opponents under 80 points. It’s a stark contrast to the nearly 120 points that the Celtics were giving up each night over the first seven games of the season.

After Monday’s embarrassing and disappointing loss to the Bulls, the air suddenly feels a lot better around the Celtics. Team meetings make for catchy headlines, but it’s winning that is the best cure for team-wide woes. And more importantly, it’s how a team wins that is the better indicator.

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With the Boston defense proving that it can shut down one of the best offenses in the league on Thursday night, the Celtics are indeed heading in the right direction after a frustrating start to the week.