The worst part was, you could see it developing as it was happening, all of it practically in slow motion. The Nets had played superb ball for 11 ½ minutes in the second half, turned a 15-point deficit into a five-point edge. Now they clung to a skinny 114-113 lead. Kevin Durant missed a 3-point prayer at the buzzer. 

There were 15 seconds left. The Celtics had a timeout. They didn’t use it. Here the Celtics came, and the ball started in Jaylen Brown’s hands and he found Marcus Smart. Smart thought for a second about shooting as the seconds melted away but split a double-team instead. And there was Jayson Tatum, cutting to the basket with just enough time to lay the ball in before the clock showed 0.0. 

Celtics 115, Nets 114. 

Celtics 1, Nets 0, in this best-of-seven opening round of the Eastern Conference playoffs. Although it feels like more than one game, even if all the Celtics did was hold serve. 

“That a tough loss, man,” Kevin Durant said. 

Kyrie Irving, as has become his custom at TD Bank Arena, won his individual battles with his Celtics demons, and he also doubled-down with the steel-lunged fans who relentlessly taunted him all day. 

Everyone from his coach to his fellow superstar Durant marvels at how he’s able to ignore the sound and the fury. But the fact he flashed the finger, and also offered an off-color remark, shows he does hear it. 

“This is not my first game at TD Garden,” Irving said. 

And then: “There’s no hostility involved.” 

And then: “It’s the dark side. Embrace it. Embrace it.” 

And Irving was brilliant — finishing with 39 points including 6-for-10 from 3. The more he lit up the fourth quarter, the more the fans started to seem downright petrified. 

But the Celtics managed to double him up on the Nets’ final possession, meaning the best the Nets got was a heave that was even outside Durant’s considerable comfort zone. 

Heartbreak for Brooklyn. 

And a feel-good start to the series for Boston. 

As the Nets go back to the drawing board for Game 2 it’s fair to wonder: Should they really be looking for anything they did too wrong? By rights, that was a win. There but for a stray second it all ends happily for Brooklyn. 

Durant, for one, was displeased by how he played. 

“They did a good job of forcing me away from the basket, forcing me into the paint. I need to be more fundamental with my moves, got to slow down. Both teams played solid.” 

Said Irving: “We’ve all been through playoff games. We know what to expect. And we know they’re not over until you close them out. You can be up five late in the playoffs and then that’s just all about what you have to go through.” 

One thing you can take to the bank about the Nets? They will not spend a lot of time the next few days feeling sorry for themselves. They are a relentlessly confident bunch, and losing one road game doesn’t put any extra hazardous signs on what they already knew was going to be a precarious four-round tour to a championship. 

And you have to believe the Nets — specifically Kyrie Irving — believe they have the upper hand when it comes to the mind games he and Celtics fans are playing together. In a perfect world, both sides would get over that soon, before uncomfortable becomes ugly, and we all know how it could go ugly. 

Irving is too good a player to get caught up in that. Sunday he was the best player on the floor, and also a lightning rod. The Nets don’t need that.