PHILADELPHIA — When the Philadelphia 76ers improbably defeated the Boston Celtics and advanced to the second round of the Eastern Conference playoffs, most knew it would be difficult for them to beat the New York Knicks.

Still, even if the oddsmakers and analysts didn’t think Philadelphia had a chance, the 76ers believed they could beat a very good New York team four times in seven games. After all, as Philadelphia star Joel Embiid pointed out, this was a more talented group than the one that lost to the Knicks in the first round two years ago. Most thought the Sixers could at least cause some problems.

What most didn’t expect was a 3-0 deficit after New York’s 108-94 win Friday night at Xfinity Mobile Arena. Now, it’s difficult to imagine anything other than a New York sweep. This series, electric in its ambiance, has been a laugher in reality. The Sixers were blown out in Game 1. They were competitive, but inferior in the clutch, in Game 2. They threw what looked to be their best shot in Game 3, and the Knicks just keep trucking.

A series in which Philadelphia thought it had a puncher’s chance has come down to an attempt to delay what looks inevitable. Sunday afternoon, the 76ers will try to extend an up-and-down season. They’ll try to avoid the embarrassment of a sweep. And speaking of embarrassing, Knicks fans once again took over Xfinity Mobile Arena and made it a difficult environment for the home team.

“We’re in a situation where we have to go out there and get the next one and see what happens,” Sixers coach Nick Nurse said. “If you get one, it gets to 3-1, and then a series can turn pretty quickly. But we’re going to have to dig in and do some things better. We started out tonight playing great. But we had a bad stretch of defensive rebounding, and we gave up direct line drives. We just didn’t score enough. We didn’t keep the scoreboard moving.”

There have been some eye-openers in this series.

The Knicks have been able to thwart Tyrese Maxey by doubling any ball screen set for him, and Philadelphia hasn’t been able to make enough open shots to deter New York from that strategy.

And though Embiid played Friday night and, as Nurse said, gave everything he could, he is not healthy and cannot move well defensively. New York made him guard in space and took advantage of his immobility defensively, consistently finding easy shots with him on the floor.

Embiid’s presence put the 76ers in a conundrum. They weren’t able to defend effectively with him on the floor. But they weren’t able to score effectively without him. When Embiid had a run of health in the last series against Boston, he was dominant on both ends. But the wear and tear of the every-other-day series format has caught up to him, and it has gone a long way toward torpedoing the 76ers.

For much of this season, the 76ers have embodied the grit and toughness of their city. There have been injuries. There have been bumps in the road. But the Sixers have saved their season multiple times. Just two Sundays ago, the end looked near. The Sixers were down 3-1 to the Celtics and heading to Boston for an apparent clincher. Instead, Philly won three straight and took the series.

Does this team have one more miracle left?

“I think we have to stay swaggy,” Philadelphia forward Kelly Oubre Jr. said. “This team has told a tale of resilience. Whenever we’ve had our backs against the wall, we’ve fought hard. We are the ones who dug ourselves this hole. We’re the only ones who can dig ourselves out of this hole. But we have to clean up a lot of mistakes. We have to go and look at the film and see where they are burning us. But at the end of the day, we have to try and just get one. That’s all that matters at this point.”

Friday night, the bad habits that limited the 76ers for most of the season showed up again. Philadelphia is a bad defensive rebounding team, and it allowed bushels of offensive rebounds in Game 3. The Sixers aren’t a great shooting team. After a hot start and a 9-2 lead, they went cold for long stretches. Defensively, the 76ers couldn’t keep Jalen Brunson from getting to the spots he wanted to on the floor. And the Sixers’ role players couldn’t match those of the Knicks, who made shots around Brunson when it mattered.

The Knicks’ potency has put pressure on the Sixers to play as cleanly as possible, and they haven’t done that. In Game 2, Philadelphia was done in by turnovers, thwarting its best chance for a win in this series. Defensive rebounding, missed shots and a lack of depth were the issues in Game 3.

“We have to add a game to it,” Maxey said. “We have to just come out and try and get a game. We have to take it one possession at a time and one play at a time. But most importantly, we have to play with some pride and not get swept on our home floor.”

If the Sixers don’t want Sunday to be their last game of the season, a lot will fall on Maxey, especially with the uncertainty over whether Embiid can play. Brunson, in his brilliance, has proven resistant to any schemes the Sixers have cooked up, beating every defender and every coverage Philadelphia has thrown at him. Maxey has to find a way to do the same, even though he shot 8-for-12 from the field Friday night and generally played well.

His teammates will have to help by making some open shots to punish New York for double-teaming Maxey.

“We just have to make some shots,” Maxey said. “We have to limit rebounds. We have to keep playing together and playing the right way. Hopefully, that will benefit us.”