BOSTON — A TD Garden worker climbed a yellow ladder set under the basket closest to the Celtics’ bench, delaying the start of Wednesday’s second half as he replaced the net thread by thread. And with 2 minutes, 22 seconds remaining in the third quarter, the ladder and net adjusters returned.

But the new twine could not solve the the Sixers’ ongoing offensive woes.

Philly shot 37.1% from the floor — and whiffed on its chance on the decisive final possession ― in an 88-87 loss to the Celtics Wednesday night to open a four-game road trip that continues Friday at Atlanta before back-to-back games at Charlotte on Monday and next Wednesday.

Despite those struggles, the Sixers had a chance at the game-winning shot. But the Sixers could not get the ball to star Joel Embiid on a switch against a smaller defender, and Jaylen Brown ended up blocking a Georges Niang shot at the buzzer.

“What we were looking for was there, honestly,” coach Doc Rivers said. “We didn’t get it there, and then I thought the execution after that wasn’t great.”

» READ MORE: Tyrese Maxey emerged as COVID-19 ravaged the Sixers. Now he’s readjusting to life with Joel Embiid

The Celtics ultimately took control when, with the score tied at 82 with about two minutes to play, Jayson Tatum hit a falling jumper, Seth Curry turned the ball over after stepping on the baseline and Dennis Schroder hit two free throws to make it a two-possession game. A Danny Green three-pointer with less than 30 seconds to play and a Schroder miss at the other end set up Philly’s final possession.

This was another offensive clunker for the Sixers. They were able to survive Monday against the tanking and rebuilding Orlando Magic. But they could not overcome Embiid, Tyrese Maxey, and Tobias Harris combining to shoot 10 of 41 from the floor against a Celtics team that is projected to make the playoffs but entered Wednesday with the same 11-10 record as the Sixers after facing similar roster instability during the early season. Philly played its normal starting lineup in back-to-back games for the first time since Games 5 and 6 in late October.

“We’ve got to get Joel going, number 1,” Rivers said. “We get him going, the whole team gets going. But that’s two games in a row where I thought [we were] lackluster. Execution is really bad right now.

“I’m not concerned by it. We’re gonna get through it. We’re just dropping games while we’re getting through it.”

Curry led the Sixers with 17 points.

Embiid’s struggles

Embiid (13 points) has struggled from the floor since returning from his bout with COVID-19. But not quite like this.

The All-Star big man missed 14 of his 17 shots Wednesday night, failing to connect under the basket and on jumpers that have typically been smooth throughout his career. The most comfortable he looked was when he stepped into a three-pointer that gave the Sixers a 59-54 lead with about four minutes to play in the third quarter. Embiid also missed four free throws but contributed 18 rebounds, six assists, three blocks and two steals.

» READ MORE: With their roster intact and a tough road trip ahead, we’re about to learn a lot about the Sixers

It was Embiid’s worst offensive performance since a November 2019 game against Toronto, when he went 0-for-11 from the field. Later that season, he went 1-for-11 against the Celtics.

Embiid acknowledged that, after his illness and extended absence, “It’s gonna take me a while to get back, especially legs and cardio and all that stuff.” He also said his hand got hit during the first quarter by Enes Freedom (formerly Kanter), saying he felt it most while shooting free throws.

“That’s what happens when Freedom has too much Freedom,” Embiid quipped. “... Hopefully it gets better, but it was pretty painful the rest of the way.”

But Embiid was uncharacteristically inconsistent with his shot even before he went into health and safety protocols. In a small sample size, he was shooting a career-worst 42.9% from the field entering Wednesday. Earlier in the season, he acknowledged he was still getting adjusted to the NBA’s new ball, but also said he needs to adjust to swarming defenses.

“The whole season I haven’t gotten any easy ones,” Embiid said. “It feels like I gotta work for everything, so that’s why I say we gotta communicate. I got to let my teammates and my guys know, probably got to come up with it myself, find ways I can get easy ones. ...

“Most of the time, if I want to get a shot off, I got to go with fadeaways and shooting off the dribble. No team is really allowing me to get to the paint from the time that I put the ball on the floor. They’re always sending doubles.”

Yet Embiid was not the only Sixer who had troubles making shots Wednesday. Harris finished 4-of-11, while Maxey went 3-of-13.

Shake’s spark

With the offense sputtering — the Sixers started 3-of-15 from the floor to trail 16-4 — coach Doc Rivers made Shake Milton his first sub about four minutes into the first quarter.

The backup point guard provided the much-needed jolt, making his first five shots including a transition layup to nearly singlehandedly bring the Sixers back from a double-digit deficit and cut Boston’s lead to 21-20. Rivers also put Milton in late in the second quarter, and he delivered the bucket that cut the Celtics’ lead to one in the first half’s final minute. Milton finished with 16 points on 6-of-11 shooting.

“We needed the lift,” Rivers said of Milton.

Niang, who hails from nearby Lawrence, Mass., was also a factor off the bench, scoring 12 points on 4-of-10 shooting. He connected on a couple of big buckets before subbing out in the fourth quarter, including a finish inside that gave the Sixers a 71-69 lead with less than nine minutes to play.

Rivers also praised backup center Andre Drummond’s energy, and the defense Matisse Thybulle played on Tatum. The Sixers’ bench outscored the Celtics’ 37-27.

» READ MORE: Georges Niang gets homecoming in Boston as Sixers face the Celtics

Hello again, Al Horford

Former Sixers big man Al Hoford looked primed for a big game when he dropped seven points in the game’s first four minutes, including a three-pointer and two finishes inside against little resistance.

But the Sixers largely held him in check after that. He opened the third quarter with a three-pointer but did not score again. He finished the night with eight rebounds and five blocks. He also guarded Embiid for a large chunk of the night, with perhaps his only notable blemish coming when he got baited into a late foul.

Horford did not play against the Sixers last season, when he was a member of the Oklahoma City Thunder. He rested during the teams’ first meeting, then had been excused from the Thunder by the time their second matchup arrived.