NBA BOSTON — Jayson Tatum walked into the TD Garden tunnel, waving both arms ecstatically as adoring fans screamed their delight at his cutting layup at the buzzer of Boston’s 115-114 victory over Brooklyn.

One lady brandished a white poster board with the slogan “In Tatum We Trust” scrawled in green on it.

On that final play in front of a sellout crowd of 19,156, Tatum demonstrated exactly why, capping a sequence that perfectly illustrated the level of teamwork the Celtics needed to overcome a 15-2 run to start the fourth quarter — and an unconscious 39-point effort from Boston villain Kyrie Irving — to take a 1-0 lead in this first-round series.

As we try to catch our breath before Game 2 at TD Garden on Wednesday, here are our five key takeaways:

1. Unparalleled teamwork
All but one player in Boston’s starting lineup (Daniel Theis), who combined for 98 points, scored at least 20 points, topped by Tatum, who led the team with 31 points (9-18 FGs).

If you watch his game-winning shot again, you’ll see that every Celtics player on the court touched the ball during that sequence: First, Tatum blocked a 3-point attempt by Kevin Durant, and Al Horford collected the rebound. Horford found Derrick White on the outlet pass and fired to Jaylen Brown as the guard crossed halfcourt. Brown collided with Marcus Smart, who deflected a shot.

Pandemonium erupted, with several residents wondering aloud whether Sunday’s triumph was the loudest they’d ever heard at TD Garden. Sunday was the loudest he recalls the arena being since the Celtics beat LeBron James and the Cleveland Cavaliers in the Eastern Conference playoffs in 2010.

NBA Tatum dished seven of his game-high eight dimes in the first half, as well as shooting the Celtics’ sixth game-winning buzzer-beater in franchise history. The team’s previous postseason buzzer-beater came in 2010, when Paul Pierce hit a game-winning shot.

The Celtics controlled the paint, scoring 56-32 and outrebounded the visitors 43-29 (including 14-5 on the offensive boards).

Nobody can fully stop Kevin Durant, but Boston slowed him down enough to win Game 1 by practically throwing everything at him early in the game, which hampered his ability to get into a rhythm later on.

Durant scored 23 points on 9-for-24 shooting from the field and 1-for-5 shooting from outside the arc, while committing a game-high six turnovers, including four in the first half alone. In the first half, Smart, Brown, Tatum, Horford, and Grant Williams took turns protecting Durant, limiting him to 2-for-10 shooting and seven points.

Do you recall the first sentence of this paragraph? You can’t stop Durant, who had 17 points in the second half and hit this key jumper with less than eight minutes left to give the Nets a 100-98 lead after Brooklyn came back from a 15-point deficit. The Nets have now lost five of their previous six playoff games, including four in a row on the road, while Durant (4,477 points) passes Jerry West (4,457) for eighth place on the NBA’s all-time postseason scoring list.

It’s NBA basketball playoff time. As a result, more aggressiveness, as well as loose whistles from a tightly-officiated first half, accompany it. Brooklyn had already picked up four team fouls only three minutes into the game, with Seth Curry receiving two of them. Boston had already entered the bonus by the time the game reached the 6:25 mark of the first quarter, while Brooklyn was just one foul away.

The teams combined for 18 fouls in the first quarter, which looked to contribute to a choppy first half with little game flow as the sides sought to acclimatise to the refereeing. Irving became the fourth Nets starter to pick up his fourth foul with 8:48 remaining in the game.

Irving, who was booed and baited at every step, drowned out the noise and blasted his way to a game-high 39 points, including 18 in the fourth quarter, his second-best scoring output in any quarter of his playoff career.

At the opening of the fourth quarter, Irving sank back-to-back 3-pointers to start Brooklyn’s 15-2 run, and you believed for a moment that the Nets would finally break out of their 0-42 playoff record when behind by double digits. Nope.

Nic Claxton secured the NBA  championship for Brooklyn by displaying his athleticism and ability by scoring 13 points in a quality 30 minutes off the bench. Claxton grabbed eight rebounds (six on the defensive glass) and blocked three shots while shooting 6-for-8 from the field and causing Boston problems with his putbacks. Yes, the Celtics dominated Brooklyn in the paint (56-32), but Claxton was the Nets’ main inside presence.

Andre Drummond’s foul issues undoubtedly contributed to a quiet night, as he was called for his fourth foul with 4:58 remaining in the first half.

Horford earns the title of Celtics’ unsung hero after grabbing a game-high 15 rebounds.