Jayson Tatum stole the show.

The All-Star swingman turned in yet another postseason career-high scoring performance Wednesday, lighting up Philadelphia for 33 points in a 128-101 blowout, as Boston seized a 2-0 series lead in the opening round of the Eastern Conference playoffs.

Tatum became the first 22-year-old Celtic to score 30-plus points in back-to-back playoff games, after dropping 32 in Game 1. Tatum also dove into league annals as the second-youngest player to produce 30 points or more and five-plus assists with no turnovers in the postseason since 1977-78 (when turnovers became an official statistic), according to research from Elias Sports Bureau.

And yet, that performance constituted just half the headline:

“I thought the difference tonight, though, was our bench really took a game that was not going our way and changed it,” Celtics coach Brad Stevens said. “Our bench was really good tonight.”

The statistics show Boston’s bench outscoring Philadelphia’s reserves 24-16. But the reality is the group did so much more toward changing the complexion of the game.

Sparked by the efforts of Tatum teamed with reserves, the Celtics turned a 14-point deficit at the end of the first quarter into an eight-point advantage by intermission that continued to swell well into the second half.

Joel Embiid carried Philadelphia with 15 points in the first quarter to get the 76ers off to a hot start that turned into a 14-point lead. But with 5:37 remaining in the opening frame, Stevens started sending in the subs, starting with Grant Williams for Daniel Theis, followed by Brad Wanamaker, and later Enes Kanter.

That group, with Tatum leading the charge, embarked on a 15-3 run to start the second quarter, followed by an 8-0 run that put Boston ahead by 13 points with 3:42 left in the first half. From the start of the second quarter to the 3:42 mark, Boston outscored Philadelphia 27-8.

“Our whole disposition changed when we went to the bench,” Stevens said. “I just thought it was much tougher as far as every possession was more challenged. We didn’t start the game well, and they started great. They made every shot, credit them for that. But I just thought from that point on, I never would’ve thought we would’ve stayed with that group in the second quarter for that long, and to their credit, I couldn’t take them out. They were playing great together and turned the game around for us.”

Tatum, Jaylen Brown and Kemba Walker combined for 44 points in the first half, while reserves Williams, Wanamaker and Kanter contributed 17.

With starting forward Gordon Hayward out due to a Grade 3 right ankle sprain that could sideline him a month, the bench contributions were timely.

“We always pretty much have confidence in our bench,” Walker said. “Tonight, they really just came out and showed the world that they’re really good. Those guys can hoop, man. When their names are called, they’re always ready. Grant, Romeo [Langford], two of our rookies were unbelievable tonight. Brad Wanamaker, who is one of our leaders, holding it down on the bench. He was tremendous. Enes, he was great as well. We need those guys big time, and tonight was a perfect example of that.”

The onslaught only continued in the second half once the starters returned, as Boston outscored the Philadelphia, 33-18, in the third quarter.

“Especially at the start of that third quarter, they really killed us in transition,” Embiid said. “Just like that, they were up 20.”

The question for the Sixers now is where do they go from here down 2-0, missing one of their top players in Ben Simmons, who is out with a knee injury, as the team starves for contributions from players on the roster other than Embiid?

Embiid scored a playoff career-high 34 points but mustered just 12 points in the second half. Tobias Harris, meanwhile, has scored 28 points in two games this series on just 30 total field goal attempts, while Al Horford has contributed just 10 points while taking just 10 shots this series.

The Sixers are also shooting just 29% from 3-point range through the first two games.

It’s clear that Embiid can’t do it all alone. That didn’t stop him from echoing his exact words coming out of the Game 1 loss after this one.

“I’ve got to do more,” he said. “That first quarter, we were great. We moved the ball. We were dominating. We got stops. They just started making stuff tough for us.”

76ers coach Brett Brown changed the team’s tactics for Game 2 after gambling on the team’s size in physicality in the series opener, only to be burned along the perimeter by Tatum and Brown.

… Their shot-makers went bananas. Tatum is a handful.”

Sixers coach Brett Brown

For this game, Brown elected to start Matisse Thybulle, who came off the bench in Game 1 and in spurts limited Tatum to just 4 points (2-9 FGs, 0-for-1 on 3-pointers), while the Celtics forward scored 18 points on 7-for-11 shooting (2-for-4 on 3-pointers) Monday when guarded by Josh Richardson, Harris and Embiid.

Thybulle couldn’t slow Tatum this time. Tatum drained 12 of 20 attempts, including 8-of-12 from 3-point range; Walker chipped in 22 points and Jaylen Brown contributed 20.

“I think it gets deflating when their shot makers went bananas,” Brett Brown said. “Tatum is a handful.”

With Philadelphia now sitting in the difficult position of needing to win four out of the next five games — provided it gets to that — to win the series, Brown said he believes the team possesses enough talent and character in the locker room to rally from the deficit.

“People are people,” Brown said. “I’m sure in the light of day, in the dark of night, you’re gonna start thinking ‘What do we have to do?’ But I do believe it. I think that there has been enough success, not consistently in the bubble, where you can call upon things without Ben [Simmons] that you can point to that are real. So, it’s up to me to recognize those things, to point them out in a real way to help them get through this. I do believe that the locker room feels they have a hell of a lot more to give.”

As for Tatum, he’s got plenty left to contribute, too. But the third-year veteran admits he’s still learning.

“I’ve got the utmost confidence in myself, and my teammates, and I know it’s reciprocated,” Tatum said. “I’m just trying to figure it out, trying to figure out when I need to be more aggressive, when I need to make the late pass. I think the most important thing is I want to be that guy. I want to be able to make big plays, whether that’s scoring or making the right pass because I’m drawing attention. I think that’s the first step: wanting to be that person.”

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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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