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BOSTON -- It's not rare to see a playoff game turn on a single play. But it's quite something to witness when nine players on the court are standing still.

Game 1 of this massive Eastern Conference semifinal matchup between the Philadelphia 76ers and the Boston Celtics, a contest in which MVP finalist Joel Embiid was ruled out because of a sprained knee, turned on one such awkward moment Monday night.

An unexplainable errant pass.

A collective shell-shocked reaction.

And a free basket that helped change the outcome in the 76ers' 119-115 victory.

The hero of the play was Tyrese Maxey -- playing with five fouls and finishing off one of the best defensive possessions he has had this season -- who was so stunned he almost turned around while sprinting down the court to see if he was the victim of an elaborate practical joke.

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There were 33 seconds left. The Celtics had the ball up by a point, with a chance to put a choke hold on the game.

"We started out looking like we were in zone, but we were actually in man[-to-man]," 76ers coach Doc Rivers said. "We switched everything trying to keep them in front of us."

The 76ers defended four different Celtics' actions on the play.

Jaylen Brown tried to drive but was stopped by Tobias Harris, so Brown pump-faked and passed the ball out.

"It was just us scrambling," Harris said. "All we know and understand is that they've got five guys out there who can create shots and create shots off the dribble."

The ball then went to Marcus Smart, who wanted to take a 3-pointer but was smothered by Maxey. Smart drove and kicked it to Jayson Tatum, who saw Maxey recover and close out to him to force another pump fake.

"We got them off the 3-point line two or three times," Maxey said. "Once I got Tatum off the 3, I looked to the other end and saw [on the shot clock] there was no time to shoot."

Tatum had passed to Malcolm Brogdon, who tried to drive but ran into a James Harden-P.J. Tucker double-team. And then Brogdon, this season's NBA Sixth Man of the Year who had 20 points in the game, got rid of the hot potato with a desperation fastball that could end up being a crux of the Eastern Conference playoffs.

"Mistake," Brogdon said. "Turnover. It happens."

The ball zoomed past Tatum's head, the apparent target, with alarming speed and landed in Maxey's hands with 0.1 seconds left on the shot clock. That tenth of a second was everything.

It made it possible for Harden to put the 76ers back in front with the last of his 45 points on a 3-pointer 21 seconds later (after Tatum had given Boston the lead with a pair of free throws). Harden's incredible performance was not in vain. Considering his personal ledger of not delivering in pressure postseason moments, it perhaps would have been lost to history had it come in a defeat.

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Game 2: Lakers at Warriors, 9 p.m.

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Game 3: Celtics at 76ers, 7:30 p.m.
Game 3: Nuggets at Suns, 10 p.m.

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Game 3: Knicks at Heat, 3:30 p.m. (ABC)
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It gave the 76ers home-court advantage in the series against a team that had owned them during the regular season, beating them three out of four times.

It gave huge comfort to Embiid, not only because it got his team a victory without him, but it relieves pressure on the need for him to return in Wednesday's Game 2. The 76ers and Embiid are hoping he will continue to improve after a platelet-rich plasma treatment last week on the injured lateral collateral ligament in his right knee, but he had not been able to do any running as of Monday night. Knowing they will go back to Philadelphia for Game 3 with no worse than a split, it provides some more options for the forthcoming decision on whether to play him in Game 2.

Only, it almost didn't.

When that split second ended as Maxey caught that laser beam pass, the shot clock buzzer sounded. And it was such an odd sight anyway -- a Celtics player passing the ball directly to the opponent in position to easily run toward the other end -- the buzzer stopping play was the only logical response.

And so everyone stood still. The fans at TD Garden watched without appropriate emotion, not quite comprehending what they were seeing.

"I was like, 'Wait a minute,'" Rivers said. "I looked, and there was no one moving. It was the strangest -- maybe one of the strangest plays I've ever seen. It was a half a second difference. If the ball had been in the air, then it's a 24-second violation."

Go frame by frame. Maxey got the ball in the smallest of windows. And the referees let him play on.

"We all thought it was a shot clock violation," Tatum said.

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"That was crazy, no cap," 76ers center Paul Reed said. "'Cause I ain't going to lie: I thought it was going to be a 24-second [violation]."

Maxey offered his take.

"I caught it, and I'm running and I don't know if I heard the whistle or the horn -- just as I was about to pick the ball up," he said. "I'm so glad I just kept going. But man, it's the right place, right time."

It wasn't even clear in the arena that the basket really counted until the scoreboard recorded it after the Celtics called a timeout. Maxey had gone so quickly there were still 28 seconds left, not only getting the 76ers the lead but also assuring his team a 2-for-1 opportunity and the last shot, if needed.

That last possession ended up going to Harden, who nailed a brilliant step-back 3-pointer to break Boston's heart.

"For the record, [Maxey] got to the free throw line and turned backwards and almost stopped because he said he thought he heard a whistle, which would've been nuts if that had happened," Rivers said.

"So I'm glad he laid it in. That's all I have to say."