The Boston Celtics are an outlying James Harden playoff performance from leading the Philadelphia 76ers 3-0 in the Eastern Conference semifinals. Two games removed from his 45 points stealing Game 1, the one-time MVP could not last a half in his home arena before the City of Brotherly Love showered him with boos.

In between, Sixers star Joel Embiid has returned on a sprained right knee, received the NBA's regular season MVP award and played his way closer to dominant form, only for his teammates to abandon him.

Embiid produced 30 points, 13 rebounds, 4 blocks and 3 assists in Friday's 114-102 loss, but the most frightening number is the 39 minutes he put on his still-recovering ligament, including the entire third quarter and the home stretch of a game Boston's Jayson Tatum put to bed with two minutes remaining.

The Celtics lead the series, 2-1. Embiid has until 3:30 p.m. ET Sunday to recover for Game 4.

Harden, Tyrese Maxey and Tobias Harris combined to shoot 10 for 36 (27.8%) in Friday's loss, and their collective defense was no better. Harris was roasted last, as Tatum scored 7 of his 27 points on three straight isolation possessions to push Boston's lead to double digits in the waning minutes. The Celtics never trailed after Marcus Smart's 3-pointer gave them a 38-36 lead with 8:34 left in the second quarter.

This after Philadelphia's second-, third- and fourth-best players shot a combined 15 of 40 (37.5%) in Wednesday's blowout Game 2 loss. The Sixers trailed for the final 43:09 of that one. They have led in only four minutes over the last two games and 15 of the 144 minutes in this series. This problem needs solving.

"Players have to show up," Embiid said. "I've gotta show up. Everybody knows their role. They have to do their job. Obviously, you can make any adjustments you want, but if players don't execute and show up and make shots, that's on us. I've gotta be better. We've all gotta be better. We just haven't been good enough."

The Celtics feel fine helping off P.J. Tucker, Jalen McDaniels and most other fifth men but De'Anthony Melton in Philadelphia's best lineups to double Embiid on every touch. When Al Horford was not Boston's first line of defense, Grant Williams hounded the MVP to the bloody end. Robert Williams III lurks off non-shooting threats to disrupt Embiid's paint touches, and the Celtics' array of guard and wing defenders swipe at his every dribble in the high post. It would be hell to pay for a healthier Embiid, as it has been in matchups past, when Boston eliminated him in no more than five playoff games in two previous meetings.

It has not helped the Sixers that Jaylen Brown has manhandled Harden since assuming the defensive assignment in Game 2, so much so that Harden repeatedly passed on opportunities to attack the basket on Friday. His discomfort was so apparent that the crowd booed each passive decision from the second quarter on. Harden has made 3-of-15 attempts from inside the arc over the past two games, reminiscent of the struggles he has experienced trying to get to the rim since returning from an Achilles injury at the end of March, including his 9-for-34 effort from 2-point range in an opening-round sweep of the Brooklyn Nets.

"We know how dominant Embiid can be," said Brown, who added 23 points, "and we know, if those other guys get going, how deadly the Sixers can be, so we just ultimately wanted to be better on defense and make it hard for everybody. I think our pressure and intensity the last two games has done that. They scored 102 points tonight, and when we keep a team in that range, we're going to be tough to beat."

The further we get from Harden's 45 points on nine days' rest in Game 1, the closer this series feels to over — unless he turns back the clock and the rest of Embiid's supporting cast solves Boston's defense. When Harden has not been a solo act in this series, he has looked like he has reservations elsewhere next week.

When asked about Harden, Sixers coach Doc Rivers said, "There were a couple of times I thought we had the lane. I thought we were trying to snake dribble more than just go straight down and make plays. That's something we talked about, getting into the paint with force and pace ... and I just didn't think we did that."

Asked about Maxey, Rivers added, "One time Jalen had it at the top and he just stood in the corner. I asked him, 'If that was Kobe Bryant, do you think he's going to stand there? No, he's going to come get the ball.'"

And asked about Embiid, Rivers finished, "As much as he was involved, there were stretches where he didn't touch the ball, and there were stretches where he didn't touch it where I thought he should have."

At some point, the coach has to wonder who will meet the moment when the pressure intensifies.

"We always talk about it," said Embiid, who is two weeks into a four-to-six-week injury. "I've gotta make the right plays, and I think I'm doing it, but I can't shoot it for them, so we've all gotta be on the same page. For us to win, I've said it the whole season, we have to be almost perfect for us to win. We don't have a lot of margins for error. Everybody has to show up and do their job, and that starts with me. I've gotta do better."

Since Embiid's Game 2 return, the Celtics have scored 123 points per 100 possessions and allowed 99, both of which would have led the league during the regular season by a wide margin. As crazy as it seems, the spread offense Harden ran in Embiid's absence felt tougher for Boston to navigate than the clogged offense they have operated since. Whether or not Embiid's injury is the deciding factor could be debated.

The 7-footer has a history of fading by the fourth quarter in the playoffs, and he was gassed by the end of the third on Friday. The Sixers are now -31 in Embiid's 66 minutes and -11 in their 78 minutes without him.

Something must give, and Philadelphia cannot count on it to be Boston. The Celtics have attempted 96 3-pointers in the past two games, mostly because Embiid's paint presence leaves shooters open each time Boston's many capable ball-handlers penetrate, and they have made 36 of them (37.5%). Clean looks open clear paths to the basket, and that was eventually the case in Game 3. Tatum and Brown both challenged Embiid at the rim and succeeded for two layups plus a foul in the opening minutes of the second half.

"We feel like we can get a good shot every time down the court," said Tatum.

In the midst of a shooting slump, Horford laughed in the face of a reporter who questioned his "elite" shooting earlier in the day, and then connected on 5 of his 7 long-distance attempts in Game 3. That is their starting center, and the Sixers have no answer if he gets hot. The Celtics are creating 33.6 open or wide-open 3s per game in these playoffs, per the NBA's tracking data, and shooting 41.4% on them.

Rob Williams is the only member of Boston's eight-man playoff rotation who does not have the green light from range. The other seven all have to be respected, and here is the thing: Tatum and Brown have made only 6-of-24 attempts at the arc in the past two games, and those floodgates will open. Tatum scored just 7 points on 1-for-7 shooting in the Game 2 blowout win, and six Celtics scored in double figures on Friday. Those waves will not stop crashing from Derrick White, Malcolm Brogdon and Smart, either.

"We don't have a lot of time down 2-1," said Embiid. "It's easy to sit here and be like, 'Oh, yeah, it's fine,' but we've gotta figure it out. You can't go down 3-1. You've gotta find a way to win Game 4."

For all the excitement Embiid's teammates felt in the conference room where he was named MVP earlier this week, the Sixers have carried none of it to the court. Another second-round playoff exit and another summer of personnel decisions await if they do not support their hobbled leader come Sunday afternoon.