The Boston Celtics can feel good but not comfortable about their 2-0 Eastern Conference semifinal lead over the Philadelphia 76ers.

With some 10 seconds left Thursday night and the shot clock nearly spent, Al Horford found himself out by the foul line with the imposing Joel Embiid between him and the basket.

But with five fouls, Embiid’s fangs weren’t as sharp. So Horford drove cleanly for a layup that threw an ice cube into what became a 108-103 victory.

The Celtics simply made the most important plays down the stretch to survive Philadelphia’s attempt to steal home-court advantage. After trusting the process these last few years, the Sixers now will have to trust their own surroundings.

And trust that they won’t get so battered in the Rookie War. While Jayson Tatum was leading the Celtics with 21 points, Ben Simmons was going 0 of 4 from the floor on the way to one single point, with five rebounds, seven assists and five large turnovers.

But the bottom line Thursday night will be the basic idea heading into Game 3 on Saturday: Take what Coach Brad Stevens said and change the particulars to get the message:

“We know it’s going to be hard,” he said around 6:45 p.m. Thursday. “We know that every game is its own entity. And we’ve known from the moment we left TD Garden on Monday night that we’re going to have to play better in Game 2 than Game 1 to win.”

Probably a lot better. For a time it seemed Philly would blow the Celtics out of their own joint.

The Sixers’ lead was as great as 22 and there was no reason to believe they were in anything but firm control when the margin sat at 20 after a pull-up jumper by the suddenly free-flowing J.J. Redick. And the needle on Philly’s who-cares meter didn’t twitch when Greg Monroe of the Celtics scored inside to make it 53-35 with 3:24 left in the half.

The Garden had by then grown a tad groggy, cranky even, as the patrons watched their nearsighted heroes make just 12 of their first 34 shots. There was little evidence of what was to come.

In fact, the 76ers’ bench didn’t appear fazed at all as the Celtics found a groove that eluded them for the first 20-plus minutes. There was no timeout forthcoming as the Celtics closed the half on a 25-8 run.

There was no administrative response when, on consecutive possessions, Terry Rozier, Marcus Smart and Rozier again drained 3-pointers and those in the stands lost their collective mind. The Celtics had made 7 of 9 shots in the key stretch and were within five at the break.

Perhaps the Sixers had been lulled into inappropriate comfort by their early success.

They had fought back perfectly against what the Celtics did to them in Game 1 and what they tried to do to them again Thursday night. The Celtics had run the Philly shooters off the 3-point line in the opener, and Coach Brett Brown’s troops countered wisely. They attacked. There were killer cuts that led to inside hoops, which begat openings on the perimeter that Redick and Robert Covington gratefully filled.

The pre-series thought here was that the Celtics would do well against Simmons and Embiid of the 76ers, but get hurt by Redick, Dario Saric and Covington.

It’s the way things were playing out much of the night, which meant the Celtics could find no real comfort in taking an eight-point lead in the third quarter.

The advantage was 79-75 heading into the fourth, and there the smallest Sixer put the bite on Boston. The 6-foot-2 – maybe – T.J. McConnell scored twice inside, then went into the forest and snared an offensive rebound that led to a Covington 3-pointer and a repossession of the lead by Philadelphia.

But the Celtics responded.

“There’s things we have to do better,” Stevens had said. “We talked about that to death the last two days. And you know that they’ll make tweaks, too. I think that at the end of the day, the tweaks will be the tweaks, but it’s, do you come with the right intensity? Do you play the game the right way? And do you do it for as many possessions as possible.”

They did.

As they’ve done all season, the Celtics stared down the deficit.

The guess here is that they’ll have to do it again if they want to get through this series. It’s 2-0 but it’s still rather tenuous.

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