Joel Embiid ignited the onslaught with two routine free throws. Tyrese Maxey pushed his team ahead with a three-pointer from the left wing. Matisse Thybulle and Josh Richardson provided the spice by jawing after Richardson whacked the 76ers’ wing streaking toward the bucket. And Maxey capped the surge with a reverse layup.

The Sixers rode a dominant first quarter to a 111-99 victory over the Boston Celtics Friday night at the Wells Fargo Center, using a 28-2 run to turn an early 10-4 deficit into a comfortable 20-point advantage that held steady for the bulk of the outing.

“There’s nights where our offense is just scoring, and then there’s nights when our defense leads to our offense,” coach Doc Rivers said. “ … [When you’re ] the other team, you get frustrated when you can’t score, and that usually trickles down to your defense.”

The emphatic win — the Sixers’ eighth in their past nine games — officially pushed them to the midway point of a strange 2021-22 regular season that has included numerous injuries and COVID-19 bouts, plus the Ben Simmons saga still lingering with less than a month remaining until the NBA trade deadline.

The Sixers (24-17) entered the night in fifth place in the Eastern Conference, then unleashed perhaps their best defensive stretch of basketball since outscoring the Atlanta Hawks 20-9 in the fourth quarter to rally for a 98-96 victory back in early December.

The 20-point halftime lead was the Sixers’ largest of the season. During those first 24 minutes, they scored 17 points off 11 Celtics turnovers, held them to 30.8% shooting (including a combined 4-for-20 from stars Jayson Tatum and Jaylen Brown) and limited Boston to 10 points in the paint.

Embiid said his goal was to start the game more aggressive on that end of the floor. Rivers added the Sixers “showed them a crowd” of multiple defenders whenever Tatum or Brown received the ball and tried to make a move, leading to deflections and overall disruption. Thybulle, an NBA second-team All-Defensive player, collected five of the Sixers’ 12 steals on the night.

“Boston is more of an iso-heavy team, so it kind of becomes easier to kind of load up and try to stop them,” Embiid said “ … We challenged our perimeter guys to contain the ball, and I think they did that tonight.”

Though the Celtics briefly flustered the Sixers with their rare switch to a zone defense, Philly prevented any significant second-half rally. After a driving layup by Tatum cut the lead to 85-72 early in the fourth quarter, the Sixers answered with two Maxey free throws, an Andre Drummond tip-in, and a three-pointer by Maxey.

The Sixers next travel to Miami, which holds the second spot in the East’s standings, for a Saturday showdown.

“This is a tough back-to-back, but it is what it is,” said Rivers, adding he hoped the Sixers would arrive at their hotel before 4 a.m. “We’re gonna get on the plane as quickly as we can, get there, get our rest. We’ll be ready.”

Embiid’s scoring streak ends

After eight consecutive games with 30 or more points, Embiid finished with 25 points, 13 rebounds, and 6 assists. He shot 7-of-15 from the floor, but went a perfect 9-of-9 from the free-throw line.

He re-entered the game with 22 points about midway through the fourth quarter. He missed a corner three-pointer early in that stint. He tried to posterize Aaron Nesmith with a one-handed driving dunk, which clanked off the rim and drew an offensive foul. He hit a three-pointer from the top of the key with about four minutes to play, then exited the game less than a minute later.

“I was aware of it, but was really not chasing it,” Embiid said of the streak. “In that fourth quarter, I just kept making plays, I don’t think I tried to force-feed and tried to get shots up. … Especially after the last game, we just played so bad overall, offensively and defensively, the main focus coming into tonight was getting the win.”

Early on, Embiid delighted the crowd by backing down former teammate Al Horford and hitting a jumper over the double-team. He hit another jumper in the big first-quarter run to put the Sixers up 26-12, then a late turnaround in the second period to push their advantage to 48-29. His first three-pointer came early in the third.

When he converted an and-one finish later in that period, he raised his arms to a cheering crowd that then began “M-V-P!” chants as he stepped to the free-throw line.

Help from his friends

Embiid did not need to be as dominant because he got significant contributions from his teammates.

Three other Sixers finished with at least 17 points, led by Maxey’s 23 on a blend of bursts to the basket and knocking down 5 of his 7 three-point attempts. He also dished out 5 assists.

Maxey said that, after about 12 days confined to a hotel suite while in COVID-19 health and safety protocols, he felt “more comfortable getting my wind back” compared to when he shot 4-of-13 during Wednesday’s return against Charlotte. Rivers also liked how Embiid made a more deliberate effort to get the ball to Maxey in transition during the second half.

“We want him to go,” Rivers said of Maxey. “We need a couple coast-to-coast plays out of him. We haven’t gotten that lately, but we’re trying to get it back.”

» READ MORE: Tyrese Maxey charges ahead

Tobias Harris added 17 points and nine rebounds. Seth Curry struggled from the floor (5-of-12), but finished with 17 points and 7 assists.

And without veteran wing Danny Green, Thybulle (8 points, 4 rebounds, 5 steals, 2 blocks) was everywhere on the court until leaving the game in the second half with shoulder soreness. He took a scary fall in the third, landing hard on his back after Dennis Schoder made contact on the way to the basket for a flagrant foul.

He scored the game’s first points on a cut to the basket to take the feed from Embiid. He leapt for a fantastic block on Brown, then swiped the ball out of mid-air. After missing both free throws following the flagrant foul, Thybulle buried a corner three-pointer to extend the Sixers’ lead to 67-45. And he was the defensive catalyst all night.

“You can tell he loves these types of matchups,” Embiid said of Thybulle. " … JT [Tatum] has really struggled against him. He has length and he’s athletic getting into passing lanes [and is] able to recover. That’s huge. Every team needs that.

“I always tell him to be as aggressive as he wants, because I’m back there and I’m gonna cover anything. Hopefully he’s OK.”

Embiid also called both flagrant fouls committed on Thybulle a “couple dangerous plays.”

“Usually he doesn’t respond to anything,” Embiid said. “But you could tell on both fouls, if he’s reacting, something must be wrong.”

» READ MORE: Doc Rivers expects the Ben Simmons saga to create ‘some crazy rumors’ around trade deadline

Not-so-welcome back

Horford and Richardson received a Philly welcome — aka plenty of boos — as members of the rival Celtics.

Horford scored the Celtics’ first five points on a corner three-pointer and a jumper over Harris, but missed his three shot attempts after that. He and Embiid swapped words in the first half when, after Embiid swiped the ball away, Horford sent Embiid to the deck near the Sixers’ bench.

Richardson, meanwhile, was booed every time he re-entered the game after his flagrant foul and words with Thybulle. He finished with 5 points and 4 rebounds in 18 minutes.

“It happens, but you gotta just keep focusing on you,” Embiid said of the chippiness.