BOSTON — Jayson Tatum strutted into the tunnel at TD Garden, raising both arms elatedly as adoring fans belted shrieks of joy celebrating his cutting layup at the buzzer of Boston’s 115-114 win over Brooklyn.

One woman held a white poster board with a message scribbled in green that said: “In Tatum We Trust”.

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

That play leads off our five takeaways as we try to catch our breath in anticipation of Wednesday’s Game 2 at TD Garden:

1. Ultimate team effort

All but one player (Daniel Theis) in Boston’s starting lineup — which combined for 98 points by the way — scored at least 20 points, led by Tatum, who poured in a team-high 31 points (9-18 FGs).

If you re-watch his game-winner, you’ll notice every player on the floor for the Celtics touched the ball during that sequence: First, Tatum contested a Kevin Durant 3-point attempt, and Al Horford grabbed the rebound. Horford found Derrick White on the outlet pass, and as the guard crossed halfcourt, he fired to Jaylen Brown. Brown hit Marcus Smart, who passed on a shot to find a cutting Tatum, who spun around Irving for the buzzer-beating layup.

“That’s kind of a microcosm of our season,” said Celtics coach Ime Udoka. “Jaylen could’ve forced the shot on [Goran] Dragic. He saw three guys on him, kicked it to Marcus [who] could’ve forced the shot over two guys. He pump-faked it, could’ve [taken] the pull-up [shot] and saw Jayson cutting. I think we’ve gotten away from the ‘your turn, my turn’ for the most part, and we enjoy seeing each other succeed.”

Pandemonium ensued, leaving many of the locals asking one another whether Sunday’s victory was the loudest they’d ever heard TD Garden. One veteran scribe said Sunday was the loudest he remembered the venue since 2010, when the Celtics knocked off LeBron James and the Cleveland Cavaliers in the Eastern Conference semifinals.

Speaking of teamwork, Tatum distributed seven of his game-high eight dimes in the first half, in addition to nailing the seventh game-winning buzzer-beater in Celtics playoff history. The team’s last postseason buzzer-beater came in 2010, courtesy of Paul Pierce.

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

2. Stopping KD

Nobody ever truly stops Kevin Durant, but Boston slowed him down enough to take Game 1 by essentially throwing the kitchen sink at him early, which likely affected his ability to get into a rhythm later in the contest.

Durant shot 9-for-24 from the field and just 1-for-5 on 3s for his 23 points, committing a game-high six turnovers, including four in the first half alone. Smart, Brown, Tatum, Horford and Grant Williams all took turns guarding Durant in the first half, limiting him to 2-for-10 shooting and just seven points.

Remember the first sentence in this entry? You don’t ever truly stop Durant, who finished with 17 points in the second half, and nailed this big shot with a little more than eight minutes remaining to give the Nets a 100-98 lead as Brooklyn rallied from a 15-point deficit. Durant (4,477 points) passed Jerry West (4,457) to move into eighth on the NBA’s all-time postseason scoring list, but the Nets have now lost five of their last six playoff games, including four in a row on the road.

Udoka spoke before the game about the extra time Boston had in preparing for Brooklyn, and surely slowing down Durant was a topic of conversation.

3. Foul-fest in TD Garden

It’s playoff basketball. So, naturally, increased physicality accompanies it, along with loose whistles from a tightly-officiated game in the first half. Just three minutes into this one, Brooklyn had already racked up four team fouls — with Seth Curry being called for two within that span. By the time the game reached the 6:25 mark of the opening quarter, Boston had already entered the bonus, while Brooklyn sat just one foul away.

In the first quarter alone, the teams committed a combined 18 fouls, which seemed to contribute to a choppy opening half with very little game flow as the teams tried to adjust to the officiating. With 8:48 left to play, Irving became the fourth Nets starter to accumulate his fourth foul.

In all, the teams combined for 50 fouls. Surprisingly, nobody fouled out.

4. Epic Irving effort soured

Booed and provoked at every turn, Irving blocked out the noise and balled to the tune of a game-high 39 points that included him racking up 18 in the fourth quarter, which registers as the second-best scoring production in any quarter of his postseason career.

Irving drilled back-to-back 3-pointers to start Brooklyn’s 15-2 run at the start of the fourth quarter, and you thought for a minute the Nets would finally break out of their 0-42 record in the playoffs when trailing by double digits to start the final frame. Nope.

What’s worse is Irving diminished arguably the greatest individual performance thus far in the playoffs with some of his antics at TD Garden. He flipped the bird to fans at TD Garden in the third quarter, and there’s a video circulating of Irving seemingly shouting an obscenity at a fan as Brooklyn headed toward the locker room at halftime.

Fines are coming.

5. Unsung heroes

Nic Claxton earned that title for Brooklyn, flexing athleticism and versatility in scoring 13 points off the bench in a quality 30 minutes. Claxton gobbled up eight rebounds (six on the defensive glass) and blocked three shots, shooting 6-for-8 from the floor, in addition to giving Boston fits with his putbacks and defense. Yes, the Celtics dominated Brooklyn in paint scoring (56-32), but Claxton provided most of the Nets’ presence inside.

Andre Drummond’s foul trouble likely contributed to a relatively quiet night, as he was whistled for his fourth foul with 4:58 left in the first half.

Horford receives unsung hero status for the Celtics after pulling down a game-high 15 boards.

“Some of the things don’t always show up on the stat sheet,” Udoka said of Horford. “He does everything we’re asking for from guarding the bigs, playing the touch coverage, to switching and guarding some of these guys. We knew we’d have an advantage on the glass, especially when they go with their small lineups and they’re switching. We can take advantage of that. He had a great night.”

Michael C. Wright is a senior writer for NBA.com. You can e-mail him here, find his archive here and follow him on Twitter.

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