BOSTON -- Philadelphia 76ers All-Star center Joel Embiid had one of the worst games of his career in Saturday night's 116-95 loss to the Boston Celtics at TD Garden.

Then he declined to talk about it.

After finishing with 11 points on 1-for-11 shooting to go with 5 rebounds, 4 turnovers and a game-worst minus-25 in 23 minutes, Embiid declined to talk to the media about an hour after the game had come to an end.

"I give credit to Boston's physicality ... they came at him," Sixers coach Brett Brown said. "They came at him off the dribble. I think that they were physical with him with a crowd, and we just didn't start well with him."

After Philadelphia entered Saturday night's game having won each of the teams' first three meetings this season, and after Embiid dominated in each of the two games he played in, the opening moments played out just as everyone watching would have predicted. Embiid won the opening tip against Celtics center Daniel Theis, then came down and scored the game's opening basket off an assist from former Celtic Al Horford, who was playing at TD Garden for the first time since signing with the Sixers as a free agent last summer.

For both Embiid and the Sixers, however, it was all downhill from there. Embiid would take only one more shot in the quarter -- a 3-pointer that he missed -- and he committed all four of his turnovers in the period, as the Celtics responded to his opening basket with seven consecutive points to give Boston a lead it would never relinquish.

Embiid never was able to get going, missing his final 10 shot attempts from the field -- four of which came from 3-point range -- and failing to get anything going against a Boston defense that was employing either Theis, a 6-foot-8 center with far less heft than Embiid, or 6-foot-6 rookie Grant Williams against him inside.

"I think it was just tough for him to get into a rhythm and get going," Sixers forward Tobias Harris said. "We have to find a way to get him some easy ones, get him some easy baskets, get him some momentum plays. Because we know when he's going, and he's got the game flowing towards him, it makes us a better team, and it picks up his game a tremendous amount."

Embiid didn't have a problem doing that in either of the first two games he played against Boston this season, averaging 26.5 points on 48.6% percent shooting to go with 13 rebounds, 4.5 assists and just 1 turnover per game. The same could be said for the Sixers as a whole, as Philadelphia's size, length and athleticism across the board gave Boston all kinds of trouble in those first three games.

But with Boston missing Kemba Walker, who sat with a sore left knee, and Enes Kanter (sore hip), and Josh Richardson remaining sidelined for Philadelphia with a hamstring injury, the Celtics looked like a completely different team in this one.

That was personified by Jaylen Brown, who, after scoring 21 points in the first three meetings combined, went off for 32 points and nine rebounds in 36 minutes, including several highlight-reel plays.

"Just trying to be aggressive," Brown said. "Trying to get a win. I haven't played as well against Philly as I would have liked the first three times, so tonight I wanted to make sure I left my imprint on the game."

While the Sixers have finished with the advantage in the season series with the Celtics with a 3-1 record, they are beginning to put themselves in a deep enough hole that it might not matter. Saturday's loss dropped Philadelphia (31-19) into sixth place in the Eastern Conference standings -- and, more important, a full five games in the loss column behind the second-place Toronto Raptors, and four behind the Celtics and Miami Heat in third and fourth places, respectively.

With road games upcoming in Miami on Monday and in Milwaukee against the league-leading Bucks on Thursday -- and with Philadelphia now sporting a brutal 9-17 mark away from home (the same number of losses as the Chicago Bulls and Cleveland Cavaliers) -- the Sixers could find themselves looking at a five- or six-game deficit by the end of business Thursday with just 30 games remaining in the regular season.

"I've been looking at it," Horford said when asked if he was keeping track of where the Sixers sit in the East playoff race. "I've been looking at it, for sure. We are aware of it. Obviously we are not where we want to be, but we are definitely looking at it.

"We were counting on tonight. We weren't able to get it done. We have a very difficult one going into Miami. All our focus has to be on that, and making up some ground. But it all starts with that Miami game."

"At what point?" Harris asked in response to a question about whether he's concerned with where the Sixers sit. "Probably 10 games ago."

Before the game, Brett Brown summed up Philadelphia's topsy-turvy campaign perfectly when he said, "We've had an erratic season." Just a week ago, Philadelphia dominated the West-leading Los Angeles Lakers, with Ben Simmons playing arguably the best game of his career. On Christmas Day, the Sixers routed the Bucks, and they similarly controlled the first three meetings with the Celtics.

Then there are the games like Thursday's loss in Atlanta, and Saturday's loss to Boston, that leave Brown and the rest of the Sixers scratching their heads as to how different their team can be on a game-to-game basis.

Suddenly, a team that was expected to challenge for home-court advantage throughout the Eastern Conference playoffs is now looking increasingly unlikely to have it in even the first round, let alone beyond that. But rather than worry about that, Brown said he's just trying to discover what it will take to get Philadelphia to play the way it has at its best on a far more consistent basis.

"I quietly pay attention," Brown said of where the Sixers sit in the playoff race. "But if you say what's more important -- looking at the standings and really studying them, versus do you just feel like you're playing good basketball? Do you feel like there's a semblance of order to what you're trying to do defensively and what you're trying to do offensively?

"When I feel good about that, and I don't -- at times I really do, but right now we're not equipped to go into the playoffs in the way we need to go into the playoffs -- that is what I think about more than the standings."