PHILADELPHIA — The pacing of basketball at its finest often resembles a boxing match. When a game of runs and momentum swings suddenly grinds into a slugfest, the two sides trading haymakers until one victor is left standing.

The Sixers and Celtics are no strangers to that dance. A pair of postseason clashes in 2018 and 2020 still linger on the periphery of their Atlantic Division rivalry. All three of top-seeded Boston’s wins this season over Philadelphia have been decided by single digits, the latest being Saturday night’s 110-107 win. Along with Giannis Antetokoumpo’s Milwaukee Bucks, the road to an Eastern Conference crown seems like it will run primarily through Boston as well as their foes down the Northeast Corridor. All of that hot-blooded context bubbled throughout Wells Fargo Center, reaching a fever pitch when Joel Embiid stepped to the foul line with 10.1 seconds remaining, his 76ers trailing by 107-105, after each team built and squandered double-digit leads in the second half.

A venomous crowd had risen to its feet. Embiid gathered his breath. Down the right side of the lane, Jayson Tatum craned his head, pleading for veteran official Marc Davis to look out for P.J. Tucker’s burly forearm on the ensuing box out. Tucker instantly returned the favor, urging Davis to instead watch for Tatum chopping at Tucker’s own leg. Above the 3-point line, Jaylen Brown gripped James Harden’s jersey, only for the Sixers’ ball-handler to viciously thrust Brown’s grip from his torso.

The struggle between these two clubs, though, has truly taken the feel of an unproven party punching up at the big, bad contender that arrived before it. Boston and Philadelphia submerged into parallel rebuilds all the way back on the night of the 2013 NBA Draft, and yet only the Celtics have advanced beyond the second round of the Eastern Conference playoff picture ever since. Boston reached the conference finals in 2017, just a few months before trading down in the draft with these very Sixers, netting the Celtics an additional first-round pick while landing Tatum instead of Markelle Fultz. They reached that stage again in 2018, falling to LeBron James’ Cavaliers in seven games, then went back to the East’s third round in 2020, before breaking through to the NBA Finals last June. And here the Celtics remain, holding the league’s best overall record while standing as the odds-on 2023 title favorite a decade later.

“It’s an understanding. We all know what we have,” Al Horford said. “This is the first time we’re at full strength all year. We all have to make sacrifices. And every night we have so much depth that it can be anyone, any night, stepping up and doing it and we’re playing for something bigger than getting numbers individually. We’re trying to get wins and we’re trying to do it as a group, and I think tonight was a good example of that.”

Embiid’s successful free throws were all for naught. Tatum emerged from the Celtics’ huddle with 5.2 seconds remaining and confidently told teammate Grant Williams that this game was about to conclude by his hand. He raced from the opposite side of the floor out of head coach Joe Muzzula’s aggressive play design and gathered a perfect feed from Marcus Smart just past halfcourt. Then with the snap of a behind-the-back dribble, Tatum shook De’Anthony Melton loose and drained the game-winning 3-pointer from the top of the key.

Tatum was responsible for the night’s dagger, but on a night when his shooting largely lagged and five turnovers followed suit, Boston’s superior depth — certainly superior to Philadelphia’s and likely superior to many other awaiting challengers — was on full display. The Celtics have three trusted reserves in Derrick White, Grant Williams and Malcolm Brogdon who are all feisty two-way presences. Don’t forget, buried further on the bench is former first-round pick Payton Pritchard, who has proven more than capable of dusting off his jersey and carrying large stretches of the Celtics’ offensive creation. Boston officials have long believed in Sam Hauser’s viability as a 3-point marksman, a 42.1% sniper just waiting for his turn to fire.

“Team. Team, team, team,” Tatum said. “Can’t harp on that enough. We have such a deep team, we can afford one or two guys having an off night.”

The Sixers are still figuring how to best incorporate trade-deadline addition Jalen McDaniels, the lanky, athletic forward acquired from Charlotte, whom Harden appeared to trust in Philadelphia’s bench-heavy lineups — while the bearded All-Star starred on Saturday and Embiid took his well-deserved rests in between scoring 41 points. Plus-minus numbers don’t paint a complete picture, but McDaniels (-23) and stretch-big Georges Niang (-22) were massive net-negatives in Doc Rivers’ rotation. The Sixers’ head coach awarded Paul Reed only 5 minutes after poor returns from the bouncy big man. There is no telling when Dewayne Dedmon, whom Philadelphia signed on the buyout market, will make his debut, Rivers said to reporters pregame.

Perhaps most importantly, Tyrese Maxey is still chasing some level of consistency in his new role off the bench following a return from a November foot fracture. The third-year guard scored just 8 points in the loss, seeing several beautiful floaters clank painfully off the rim and out of the basket altogether.

The 76ers have now lost four-straight against Boston dating back to last season. The crowd erupted when Embiid heaved a prayer down most of the court and drained what could have sparked five more minutes of play. The moment brought an eerie recollection of that 2018 postseason series, when Sixers game-day operations launched celebratory confetti thinking Marco Belinelli’s 3-pointer clinched a victory. Then replay revealed his sneaker was dreadfully on the line, and having to sweep all those colorful cuts of paper off the floor only delayed Philadelphia’s eventual overtime loss.

Embiid ignored the ruckus in the stands following his shot. He marched right to the locker room even while officials reviewed the fruitless sequence. He was somber yet thoughtful as he fielded questions postgame, his hulking frame tucked into white sweats. He did sound defeated, but as understanding as ever that accomplishing the Sixers’ lofty goals still requires more. Right now, their best is not enough on a consistent basis. And certainly not when Boston is far ahead on this race to the proverbial mountaintop. The Sixers’ 67-52 lead in the third quarter quickly became a distant memory.

“You can never relax,” Embiid said, his head drooping down as he picked at his fingernails. “Especially in the NBA.”